List of Participants and Book of Abstracts

ScotCHEM2009 List of Participants77/1/6/41/311/ POSTER (1) Dr Eitan Abraham: Magnetic Impurities in Quasi�1D Conjugated Polymers2/ POSTER (2) Mr. Alexander Abramov: Theoretical design of ammonia borane clathrates3/ POSTER (3) Mr. Muhsen Alibadi: THE MECHANISM OF HYDROFORMYLATION OF THE ALLYL LIGAND IN Co(η3�C3H5)(CO)2(PH3)

4/ POSTER (4) Mr Panagiotis Angelikopoulos: In quest of an optimum Carbon Nanotube dispersionmechanism5/1 Dr Sharon Ashbrook: No presentation6/ POSTER (5) miss Julie Bardin: SALT FORMATION PREDICTIONS BY COMPUTATIONAL METHODS7/ POSTER (6) Mr. Ragnar Bjornsson: EFG Tensors of Transition Metal Complexes from DFT8/ POSTER (7) Dr. Henry Bock: Directed Surfactant Self�Assembly for Bottom�Up Fabrication9/ POSTER (8) Ms Lilianna Bryjko: SA�CASSCF and R�matrix calculations of low�energy electron collisionswith uracil10/ POSTER (9) Prof. Michael Bühl: Dissociation of Water During Formation of Anodic Aluminium Oxide11/2 Dr Matt Costen: No presentation12/ POSTER (10) Mr Peter Daldrop: Virtual ligand screening for Riboswitches13/ POSTER (11) Mr Michael Edie: Fuelling a Sustainable Future: Virtual Design of New Hydrogen StorageMaterials with Enhanced Properties14/3 Prof. Michel Etienne: No presentation15/4 Dr Stephen Euston: No presentation16/5 Dr Xavier Fradera: No presentation17/6 Dr Herbert Fruchtl: No presentation18/ POSTER (12) Mr Vihar Georgiev: Electronic Structure/Function relationship in Metal Nanowires:Components for Molecular Electronics19/7 Prof. Maciej Gutowski: No presentation20/ POSTER (13) Dr. Jonas Haller: Computational Studies of Tautomerisation of N�Heterocyclic Carbenesat Ruthenium21/ POSTER (14) Dr John Henry: Calculations of the electronic structure of substituted indoles predictionof their oxidation potentials, coupling mechanism and oligomer redox properties22/8 Dr Javier Hernandez Paredes: No presentation23/ POSTER (15) Dr Ben Hourahine: Fast and accurate DFT�based calculations24/ POSTER (16) Mr Cao Jie: Assessment of density functionals for the structure prediction of a Tyr�Glyconformer: Good performance of the M06�L functional25/9 Dr Blair Johnston: No presentation26/10 Mr. Zibo Keolopile: No presentation27/1/1 ORAL PRES / POSTER (17) Dr Jos Koetsier: Rapid: giving computational science a friendly face28/ POSTER (18) Mr. Tobias Kraemer: Catalytic Nitrite Reduction by a CuNiR Model Complex – AComputational Study29/11 Mr Simon Kraeusel: No presentation30/12 Dr Mark Law: No presentation31/ POSTER (19) Mrs Lorreta Lawton: Magnetic Interactions via Hydrogen Bonds and Anion/CationSubstitution effects on HB Interactions32/ POSTER (20) Dr Tomas Lebl: NMR and computational study of conformational behaviour of medium�sized ring triones33/ POSTER (21) Mr. Sanliang Ling: Interactions of Hydrogen and Methanol with the MO3 (M=W or Re)Surfaces: The Effect of Epitaxial Interface on the Reactivity34/2 ORAL PRES Prof. Stuart Macgregor: Adventures in C�H Activation35/ POSTER (22) Mr Dario Marrocchelli: The construction of a reliable potential for GeO2 from first�principles36/3 ORAL PRES Dr. Sarah Masters: What is going on? How theory helps us understand our experimentalobservations!37/13 Mr Neil McCulloch: No presentation38/14 Prof John McGrady: No presentation

39/ POSTER (23) Mr David McKay: Computational Studies of the Isomerisation of Nido� and Closo� 12�vertex Carboranes40/15 Prof Kenneth McKendrick: No presentation41/ POSTER (24) Mr Russell McKinlay: Theoretical Studies of One and Two�Photon AbsorptionSpectroscopy of Fe(CO)5 and Potential Energy Surfaces for Photodissociation42/4 ORAL PRES Dr John Mitchell: Predicting Intrinsic Aqueous Solubility by a Thermodynamic Cycle43/16 Dr Carole Morrison: No presentation44/17 Dr Abu Naser: No presentation45/ POSTER (25) Mr Robert Noble�Eddy: The hunt for (the structure of) dibenzylsulfone46/ POSTER (26) Mr. Benjamin PEIGNE: Spin delocalization into Fe(L�S)2Mo and MoFe3S4 cubanessystems47/ POSTER (27) Mr Julien Panetier: Computational Studies of Intermolecular Aromatic C�F BondActivation by a Rhodium(I) Silyl Complex48/ POSTER (28) Mr Grant Paterson: Synergy between Experiment and Theory: Exploring the CollisionDynamics of OH + Simple Partners49/18 Dr. Martin J. Paterson: No presentation50/19 Professor Douglas Philp: No presentation51/20 Mr Mohan Pilla Janakiraman: No presentation52/21 Ms Amalia Poblador�Bahamonde: No presentation53/22 Mrs Elisa RUHLAND: No presentation54/23 Prof David Rankin: No presentation55/ POSTER (29) Mr. Anthony Reilly: Understanding the effects of anharmonic thermal motion56/24 Dr Monika Rella: No presentation57/25 Dr. Qinghua Ren: No presentation58/ POSTER (30) Dr Patricia Richardson: The EaStCHEM Research Computing Facility59/26 DR MUTHULINGAM SURESH: No presentation60/ POSTER (31) Ms Evdokiya Salamanova: Molecular dynamics simulations on the halogenase PrnA61/ POSTER (32) Mr Chamil Sameera: Biomimetic water oxidation: some clues from computationalchemistry62/ POSTER (33) Dr. Jörg Saßmannshausen: From DFT to spectroscopy and back: The use of bothtechniques to unearth active compounds in homogeneous catalysis63/27 Dr Hans Martin Senn: No presentation64/ POSTER (34) Mr Lukasz Serafin: Chemical bonding properties in substituted silicon hydride isomers65/ POSTER (35) Miss Lynsey Shepherd: Fast Proton Transport through Proteins via Internal Water Wires66/ POSTER (36) Dr. Nicolas Sieffert: Non�Covalent Interactions in a Transition�Metal TriphenylphosphineComplex: a Density Functional Case Study67/28 Mr Daniel Taylor: No presentation68/29 Dr Mark Thomas: No presentation69/30 Dr Andrew Turner: No presentation70/5 ORAL PRES Dr. Tell Tuttle: Averaging Semiempirical NMR Chemical Shifts – Dynamic Effects on theSub�picosecond Timescale.71/ POSTER (37) Dr Derek Wann: A molecular dynamics approach to equilibrium structures in gases andcrystals72/31 Mrs Nuha Wazzan: No presentation73/ POSTER (38) Mr Alexander Whiteside: Computational measures of electronegativity for groups andmolecular ions74/6 ORAL PRES Prof Chick Wilson: Combining Experiment and Computation in the Study of StructuralEvolution of Molecular Materials75/ POSTER (39) Dr Ekaterina Zueva: Electronic structure and magnetic properties of a trigonal prismaticCuII6 cluster76/ POSTER (40) Ms Justyna Zurek: Computational Studies of Vibronic Effects in Inorganic Chemistry:Photostereochemistry of (BQA)PtMe2I, and the Pseudo�Jahn�Teller Effect in Mo2(DXylF)2(O2CCH3)2(P2�O)277/ POSTER (41) Dr Tanja van Mourik: Assessment of density functionals for intramolecular dispersion�rich interactions

I. Oral Presentations74/6 ORAL PRES Prof Chick Wilson: Combining Experiment and Computation in the Study of StructuralEvolution of Molecular Materials

Combining Experiment and Computation in the Study ofStructural Evolution of Molecular Materials

C C Wilson, L M Lawton, D S Middlemiss, C A Morrison and M SchmidtmannProf Chick Wilson: c.c.wilson@chem.gla.ac.uk

University of Glasgow

Much of our recent experimental work has focused on the use of X�ray and neutron diffraction to study the structural evolutionof hydrogen bonded molecular systems, including polymorphic materials, molecular complexes, tautomeric molecularmaterials, systems exhibiting hydrogen atom transfer and disorder, and magnetic systems coupled through hydrogen bondmotifs. In particular we have focused on multi�temperature and pressure approaches to these studies, revealing often subtlebehaviour of the hydrogen bonding, the structural evolution and on some cases of evolution of physical properties. Some ofthese effects are sufficiently subtle as to challenge the limits of current experimental diffraction, and also to challenge ourtheories of hydrogen bond formation.

As a complementary approach to understanding these systems, we have for some years been developing applying plane�wave (periodic) density functional theory calculations for studying hydrogen bonds in the solid state. These are shown to havereal potential in the study of a variety of hydrogen bonding systems. In addition MD approaches have been developed forthese calculations, which allow us to examine the temperature evolution of molecular structures in the solid state and toquantify proton transfer effects. This leads to a fuller understanding of hydrogen bond formation and offers an improveddescription of the structural evolution observed in experiments.

These approaches will be illustrated by results from a range of studies including: proton migration and transfer systems;materials with potentially cooperative hydrogen bonding; tautomeric hydrogen bonded systems in which very smallexperimental energy differences can be reproduced and understood; prediction of energy scales for polymorphism inmolecular complexes; optimisation of magnetic coupling in Prussian Blue Analogues and in related materials by design ofsimple hydrogen�bonded linkages.

36/3 ORAL PRES Dr. Sarah Masters: What is going on? How theory helps us understand our experimentalobservations!

What is going on?How theory helps us understand our experimental observations!

Sarah MastersUniversity of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ; s.masters@ed.ac.uk

X�ray diffraction is ubiquitous within chemistry departments across the UK and would probably be mostpeople’s first port of call to determine a molecular structure. However, gas electron diffraction is anexcellent technique for the determination of structures that are free from the intermolecular interactionsthat can affect solid�state structures. When the observed structures are very different between the solidand gaseous phases, we want to try to rationalise what is happening and this is where theory is veryvaluable. Data obtained from calculations can help us to understand our experimental observations. Usingthe structural investigation of N�methyldichloroacetamide as an example, this presentation will outline thefirst structural investigation in the solid and gas phases to utilise both experimental and computedinformation, outlining how theory helped us understand just what was going on.

27/1/1 ORAL PRES / POSTER (17) Dr Jos Koetsier: Rapid: giving computational science a friendly face

Rapid: giving computational science a friendly faceJ. Koetsier, A.R. Turner and J.I. van Hemert

Dr Jos Koetsier: jkoetsie@staffmail.ed.ac.ukUniversity of Edinburgh

Rapid is a unique approach to quickly designing and delivering web portal interfaces for applications that require largeamounts of computing resources or that need to run on specific servers. The approach consists of defining the resources,application use and user interface in one XML file. This file is then validated and translated directly into a live portlet that can beinserted into a portal container. The whole process can be performed without any conventional programming. Rapid providesall the necessary components for handling compute�jobs. It knows how to handle remote files stores, monitor jobs, validateinput, talk to Sun Grid Engine, Condor, PBS or just use a plain SSH connection.

Here we show a portal for teaching undergraduate chemistry students about structure and bonding of simple compoundsusing Gaussian 03. It was created by Andrew Turner using Rapid for the Rapid Chemistry Portals by Engaging Researchersproject. The whole process took him just several days.

34/2 ORAL PRES Prof. Stuart Macgregor: Adventures in C�H Activation

Adventures in C0H ActivationS. A. Macgregor, A. I. Poblador�Bahamonde, L.J.L. Haller

Prof. Stuart Macgregor: s.a.macgregor@hw.ac.ukHeriot�Watt University

The activation of C�H bonds by transition metal centres presents a fascinating array of mechanistic possibilities.Computational chemistry is particularly important in this field as it allows the delineation of competing mechanistic alternativesand provides insight into the factors controlling the C�H activation process. We will present results on two recent studies of'electrophilic' C�H activation. The cyclometallation of arylamines at Pd(OAc)2 and [CpIr(OAc)]+ is shown to proceed viaambiphilic activation in which the metal centre and acetate co�ligand act synergically to promote C�H bond cleavage. Inaddition a novel base�induced cyclometallation at a cationic Ru2+ metal centre will be described where activation of a non�agostic alkyl C�H bond is seen in preference to the anticipated cleavage of a neighbouring agostic bond.

42/4 ORAL PRES Dr John Mitchell: Predicting Intrinsic Aqueous Solubility by a Thermodynamic Cycle

Predicting Intrinsic Aqueous Solubility by a ThermodynamicCycle

J.B.O. Mitchell, D.S. Palmer, A. Llinas, I. Morao, G.M. Day, J.M. Goodman, and R.C. GlenDr John Mitchell: jbom1@cam.ac.uk

Cambridge / St Andrews

We discuss methods to predict the intrinsic aqueous solubility of crystalline organic molecules from two differentthermodynamic cycles. We find that direct computation of solubility, via ab initio calculation of thermodynamic quantities at anaffordable level of theory, does not deliver the required accuracy. Therefore, we have turned to a mixture of directcomputation and informatics, using the calculated thermodynamic properties, along with a few other key descriptors, inregression models. The model includes a calculated crystal lattice energy which provides a computational method to accountfor the interactions in the solid state. We suggest that it is not necessary to know the polymorphic form prior to prediction.

70/5 ORAL PRES Dr. Tell Tuttle: Averaging Semiempirical NMR Chemical Shifts – Dynamic Effects on theSub�picosecond Timescale.

Averaging Semiempirical NMR Chemical Shifts – DynamicEffects on the Sub0picosecond Timescale.

T. TuttleDr. Tell Tuttle: tell.tuttle@strath.ac.uk

University of Strathclyde

The variation of the 1H and 13C NMR chemical shifts of heptapeptide ATWLPPR was investigated during a hybrid quantummechanical (QM)/molecular mechanical MM=CHARMM) molecular dynamics simulation of the peptide in aqueous solvent.The semiempirical method OM3 was used as the QM method and the effect of augmenting the OM3 hamiltonian with anempirical dispersion term (OM3�D) was also explored. The semiempirical MNDO method was used to calculate the chemicalshifts of snapshots taken at 50 fs intervals during the 100 ps simulation. The calculated chemical shifts are highly sensitive tofluctuations of the molecular geometry on the time�scale of molecular vibrations. However, the time�averaged chemical shiftover the full simulation result in reasonable agreement with the experimental NMR chemical shifts and more consistent resultscompared with the averaged chemical shifts obtained from gas phase optimized conformations of the peptide. The OM3 andOM3�D methods are stable, and reproduce the main features of the experimental geometry, during the 100 ps simulation.

II. Posters1/ POSTER (1) Dr Eitan Abraham: Magnetic Impurities in Quasi�1D Conjugated Polymers

Magnetic Impurities in Quasi01D Conjugated PolymersN. McCulloch & E.Abraham

Dr Eitan Abraham: E.Abraham@hw.ac.ukHeriot Watt Uni.

We investigate the effect of impurity magnetic atoms on the bipolaron formation in 1D conjugated polymers. A quantum MonteCarlo technique is used and the Hamiltonian is an extended Hubbard model including variable hopping,phonons,electron�phonon and Kondo terms. Our room�temperature simulations show that impurities break the bipolaron into two polarons.However, increasing the doping causes the bipolaron to reappear as evidenced by the lattice order parameter. As thebipolaron can be seen as a real�space Cooper pair, our result could have implications on the pursuit of room�temperaturesuperconductivity.

2/ POSTER (2) Mr. Alexander Abramov: Theoretical design of ammonia borane clathrates

Theoretical design of ammonia borane clathratesA. Abramov and M. Gutowski

Mr. Alexander Abramov: ava3@hw.ac.ukHeriot�Watt University

Hydrogen economy remains unrealized due to number of problems including hydrogen storage. High density and easyaccess to stored hydrogen are two contradictory requirements which cannot be met in known storage materials. Proposed inthis work a concept of hierarchical hydrogen storage offers a possible solution to the problem. The concept is implemented intheoretically designed clathrates built from ammonia borane and loaded with molecular hydrogen. These new materials wouldhave two levels of hydrogen storage: (i) physisorbed hydrogen and (ii) hydrogen chemically bound in ammonia borane. Theadvantages of these materials would be: (i) the fast kinetics of release of physisorbed hydrogen and (ii) very high gravimetricand volumetric hydrogen density. We developed a construction principle for clathrates of ammonia borane, performedelectronic structure calculations for isolated cages and for periodic structures built from these cages. The nature ofdihydrogen bonds between ammonia borane molecules and of guest�host interactions was analyzed within the framework ofsymmetry adapted perturbation theory of intermolecular interactions. The theoretical results indicate that hydrogen can bestored in the cages of ammonia borane.

3/ POSTER (3) Mr. Muhsen Alibadi: THE MECHANISM OF HYDROFORMYLATION OF THE ALLYL LIGAND IN Co(η3�C3H5)(CO)2(PH3)

THE MECHANISM OF HYDROFORMYLATION OF THE ALLYLLIGAND IN Co(η30C3H5)(CO)2(PH3)

M. A. M. Alibadi and J. E. McGradyMr. Muhsen Alibadi: abomuh@chem.gla.ac.uk

University of Glasgow

The mechanism OF hydroformylation of the cobalt�based allyl complex, Co(η3�C3H5)(CO)2(PH3) has been investigated at

the DFT level using the PBE1PBE functional. This reaction can lead to linear (n�propyl) or branched (iso�propyl) cobaltcomplexes as well as the corresponding aldehydes. Then hydride migratory insertion leads to the agnostically�stabilized n�propyl and isopropyl complexes, Co(C3H7)(CO)2(PH3). The major difference between the linear and branched cycles is the

CO insertion barrier, which was predicted to be 10 kcal/mol for the linear complex and 15 kcal/mol for the branched isomer,reflecting the larger steric demands of the isopropyl group with respect to the n�propyl group.

4/ POSTER (4) Mr Panagiotis Angelikopoulos: In quest of an optimum Carbon Nanotube dispersionmechanism

In quest of an optimum Carbon Nanotube dispersionmechanism

P. Angelikopoulos and H. BockMr Panagiotis Angelikopoulos: pa49@hw.ac.uk

Heriot Watt University

Carbon Nanotube materials are drawing increasing attention due to their vast range of applications. Carbon nanotubes(CNTs) form bundles due to strong Van der Waals interactions and in solution also solvent induced forces. However, mostapplications require individual tubes. Thus, preparation of stable CNT suspensions is a key step in CNT processing.

Surfactant molecules have been widely used for dispersing nanotubes. However, due to the inherent complexity of theprocess its thermodynamics is yet to be fully comprehended. This complexity originates from the competition betweensurfactant self�assembly and heterogeneity and curvature effects of the nanotube bundles. Computer simulations, employedin this study, reveal that surfactant adsorption on CNT bundles is fundamentally different compared to adsorption on individualCNTs. Our results are essential for the design of efficient dispersion methodologies.

6/ POSTER (5) miss Julie Bardin: SALT FORMATION PREDICTIONS BY COMPUTATIONAL METHODS

SALT FORMATION PREDICTIONS BY COMPUTATIONAL METHODSJ.Bardin, B.F.Johnston and A.J.Florence

miss Julie Bardin: j.bardin@strath.ac.ukUniversity of Strathclyde

Structure determination from X�Ray Powder Diffraction (XRPD) data has become a widely used tool for structural analysis inthe absence of single crystals1. Although this technique has significantly improved over the past decades, it remains limited inthe determination of hydrogen atom positions, which is especially an issue in systems where salt formation due to protontransfer cannot be excluded. PW�DFT geometry optimisations were used to complement the experimental structuredetermination of two 2,4�diamino�6�methyl�1,3,5�triazine (DMT) difluoroacetate (DFA�) salts. After structure determination withtraditional XRPD packages, geometry optimisations using the CASTEP2 program were carried out on the neutral structures toexamine whether calculations would predict salt formation. The effect of the N�H…O distance on the total energy of thesystem was also investigated: the position of the H atom was shifted along the N…O vector using the Material Studios3interface to CASTEP, so that optimisations with constrained O…H distances ranging from 0.9 to 1.7Ǻ could be performed. Inorder to investigate the suitability for our approach for predicting proton transfer, calculations were also performed on a seriesof structures previously reported in the literature. Gas�phase calculations using the GAUSSIAN034 program were used toprovide information about interaction energies between the two salt components and explain the selectivity on the DMTprotonation site. This work provides insight on the extent with which computational methods can be used to complementXRPD when salts may exist.

1 Florence et al. J.Appl.Cryst. (2005). 38, 249�2592 2001�2008 Accelrys Software Inc.3 version 4.4, Copyright @ 2008 Accelrys Software Inc.4 1995�2004 Gaussian, Inc.

7/ POSTER (6) Mr. Ragnar Bjornsson: EFG Tensors of Transition Metal Complexes from DFT

EFG Tensors of Transition Metal Complexes from DFTR. Bjornsson and M. Buehl

Mr. Ragnar Bjornsson: rb465@st�andrews.ac.ukUniversity of St Andrews

The electric�field gradient (EFG) at a quadrupolar nucleus affects spectroscopic properties such as the nuclear quadrupolecoupling constant (NQCC) and the lineshape of NMR signals. Being a tensorial quantity, the EFG provides a sensitive probeinto the electron distribution around the nucleus. Not much is known, however, about the reliability of density functionals todescribe EFG tensors of transition metal complexes. In this work, available gas�phase NQCC microwave data of first�rowtransition metal complexes are used to benchmark density functionals currently in use. Advancing up Jacob's ladder ofdensity functionals results only in small reduction of errors. Inclusion of Hartree�Fock exchange is generally beneficial, andglobal hybrid functionals like B3LYP, PBE0 and MPW1PW91 perform well. Best performance is shown by range�separatedhybrids, suggesting long�range exchange effects to be important for an accurate description of the EFG tensor.

8/ POSTER (7) Dr. Henry Bock: Directed Surfactant Self�Assembly for Bottom�Up Fabrication

Directed Surfactant Self0Assembly for Bottom0Up FabricationP. Angelikopoulos

Dr. Henry Bock: h.bock@hw.ac.ukHWU

We are developing a “tool” for the bottom�up fabrication of nanostructured materials. This tool combines two effects: thetendency of molecules to adsorb at the point of highest interaction potential in a heterogeneous environment and the self�assembly of surfactants into a number of nanoscale structures. Both effects combined provide the opportunity to constructnanoscale structures in selected regions of a heterogeneous material.Here computer simulations are used to study the formation and control of self�assembled structures on crossing carbonnanotubes. We further investigate the viability of these structures for structural and functional purposes. Because of theextraordinarily detailed insight computer simulations provide, they are excellently suited to study nanoscale systems.

9/ POSTER (8) Ms Lilianna Bryjko: SA�CASSCF and R�matrix calculations of low�energy electron collisionswith uracil

SA0CASSCF and R0matrix calculations of low0energy electroncollisions with uracil

Lilianna Bryjko, Tanja van Mourik, Amar Dora and Jonathan TennysonMs Lilianna Bryjko: lb435@st�andrews.ac.uk

University of St Andrews

A series of R�matrix calculations within the static exchange, static exchange plus polarisation and close�couplingapproximation on electron�uracil collisions are presented. Of particular interest in this system is the presence of the low�energy quasibound states of the compound system as such resonances are thought to be the key initial process in theradiation damage of living systems. Particularly as input for the close�coupling calculations, a series of target calculations areperformed which consider low�lying singlet and triplet excited states of the uracil target. Here the (14,10) active space andassociated State�Averaged Complete Active Space Self Consistent Field orbitals were used.

10/ POSTER (9) Prof. Michael Bühl: Dissociation of Water During Formation of Anodic Aluminium Oxide

Dissociation of Water During Formation of Anodic AluminiumOxide

Zixue Su, Wuzong Zhou, Michael BühlProf. Michael Bühl: buehl@st�andrews.ac.uk

University of St. Andrews

According to model computations at the B3LYP/6�311+G** level, an external electric field can facilitate the heterolyticdissociation of properly oriented water molecules significantly. Depending on the models used, the maximum predicted changeof the dissociation energy in the field is ca. �3 to �4 kcal.nm/(mol.V), and decreases with the cosine of the angle between theexternal field and the breaking OH bond. These microscopic results can be related semi�quantitatively to macroscopicobservables from mechanistic studies on the pore formation of anodic aluminium oxide, thus lending support to the equifieldstrength model and field�enhanced water dissociation at the growing oxide surface that has been put forward in these studies.

12/ POSTER (10) Mr Peter Daldrop: Virtual ligand screening for Riboswitches

Virtual ligand screening for RiboswitchesPeter Daldrop, Robert T. Batey & Ruth Brenk

Mr Peter Daldrop: p.daldrop@dundee.ac.ukUniversity of Dundee

Virtual ligand screening has become an extensively applied technique in drug discovery. However, it is virtually exclusivelyapplied to protein targets. We present an approach to use this technique for RNA targets, namely riboswitches whichrepresent metabolite dependent gene regulatory elements. Retrospective and prospective studies were carried out to validatethe method and new scaffolds of binders were predicted for the purine riboswitch, which was used as a model system. Thecomputational results were then tested by experimental methods, confirming the majority of predictions.

13/ POSTER (11) Mr Michael Edie: Fuelling a Sustainable Future: Virtual Design of New Hydrogen StorageMaterials with Enhanced Properties

Fuelling a Sustainable Future: Virtual Design of New HydrogenStorage Materials with Enhanced Properties

Michael Edie, Maciej GutowskiMr Michael Edie: chemje@hw.ac.uk

Heriot�Watt University

It is considered by many that the achievement on�board hydrogen storage (HS) is one of the major technological problemspreventing the implementation of a viable hydrogen centred economy. Materials based on the formula (BN)xHy such asNH4BH4 and NH3BH3, have been put forward as promising candidates due to the hight gravimetric and volumetric density aswell as the modest temperatures of dehydrogenation. In resent years there have been numerous experiential and theoreticalstudies into such systems, this work falling into two main groups: firstly the fundamental thermodynamic and mechanisticnature of hydrogen release in pure (BN)xHy systems, and secondly development of strategies of improving the kinetics ofdehydrogenation, via heterogeneous catalysis, nano�confinement or by ionic reaction solvation. However there are fewexamples that address the need to improve the thermodynamic performance of (BN)xHy compounds and thus achieveefficient reversibility. Our materials by design approach is based on the belief that one may tune the chemical potential ofthese materials by the incorporation of modest chemical motifs on�or�into the BN frame work. We will report computationalresults on hybrid (BN)(1�y)C2yHx compounds that might display thermodynamics of dehydrogenation intermediate betweenthis for carbon�based and that for BN based hydrides.

18/ POSTER (12) Mr Vihar Georgiev: Electronic Structure/Function relationship in Metal Nanowires:Components for Molecular Electronics

Electronic Structure/Function relationship in Metal Nanowires:

Components for Molecular Electronics

Vihar Georgiev , John E. McGrady

WestCHEM, Department of Chemistry, University of Glasgow, G12 8QQ

In the last few decades, molecular electronic devices have become an important area of research. We are

approaching the size limits of conventional silicon-based technology, so there is great interest in replacing

semi-conductor – based components with molecular analogues. Examples include carbon nanotubes,

organic molecules, polymers and organometallic molecular wires such as extended metal atom chains

(EMAC) – Fig 1. These systems are built from d-metal elements supported by oligo-α-pyridyl ligandsand can, in some cases, exist in symmetric and asymmetric form which correspond to quite distinct low-

lying electronic states1.

Figure 1: Structure of linear metal trimetal system

The geometric differences between symmetric and unsymmetric form exert a significant influence over

the electron transport properties through these chain complex. We report calculations of the conductance,

current-voltage characteristic and the transmission spectrum of these systems using DFT and NEFG

approach2and reveal the nature of the electron transport.

1 Pantazis, D.A., McGrady, J.E., J.Am.Chem.Soc., 128,4128, (2006)

2 Atomistix ToolKit version 2008.10, QuantumWise A/S (www.quantumwise.com)

M. Brandbyge, J.-L. Mozos, P. Ordejón, J. Taylor, and K. Stokbro, Phys. Rev. B 65, 165401 (2002)

J. M. Soler, E. Artacho, J. D. Gale, A. García, J. Junquera, P. Ordejón, and D. Sánchez-Portal, J. Phys. Condens. Matter

14, 2745 (2002).

J. Taylor, H. Guo, and J. Wang, Phys. Rev. B 63, 245407 (2001)

20/ POSTER (13) Dr. Jonas Haller: Computational Studies of Tautomerisation of N�Heterocyclic Carbenesat Ruthenium

Computational Studies of N�Heterocyclic Carbenes Tautomerism atRuthenium

L. Jonas L. Häller a*, Stuart A. Macgregor a, Michael K. Whittleseyb, and Michael J. Pageb

a Department of Chemistry, EPS, Heriot�Watt University, Edinburgh, EH14 4AS, UKb Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK

*J.Larsson_Haller@hw.ac.uk

The ruthenium N�heterocyclic carbene complex (1) undergoes tautomerism to

form an N�bound species (2) in the presence of excess carbene:1

Density functional theory calculations were used to investigate the tautomerismmechanism. Three processes were considered involving (i) H2�complex

formation, (ii) imidazolium formation and (iii) deprotonation by excess carbene.The role of excess carbene on these processes and the effect of different NHCligands on the relative stabilities of the C� and N�bound tautomers will also becompared.

1. S. Burling, M. F. Mahon, R. E. Powell, M. K. Whittlesey, and J. M. J. Williams J. Am. Chem.Soc. 2006, 128, 13702.

21/ POSTER (14) Dr John Henry: Calculations of the electronic structure of substituted indoles predictionof their oxidation potentials, coupling mechanism and oligomer redox properties

Calculations of the electronic structure of substituted indolesprediction of their oxidation potentials, coupling mechanism

and oligomer redox propertiesJ. B. Henry, A. R. Mount

Dr John Henry: J.B.Henry@sms.ed.ac.ukUniversity of Edinburgh

The electrochemical oxidation and polymeristation of 5�substituted indole dimers has been studied in acetonitrile. The productsof this oxidation are an electroactive film deposited onto the electrode surface, and dark green sediment. These productshave been characterised by mass spectroscopy, UV�visible spectroscopy, fluorescence spectroscopy and NMRspectroscopy.Density Functional Theory (DFT, B3LYP) calculations have also been used to determine theoretical values for the standardredox potentials of the substituted dimers. The calculations have been corrected for solvation with a Polarized ContinuumModel (PCM). Good agreement can be found between these theoretical values and those observed experimentally.

23/ POSTER (15) Dr Ben Hourahine: Fast and accurate DFT�based calculations

Fast and accurate DFT0based calculationsB. Aradi, Th. Frauenheim, T. Heine, B. Hourahine, T. Niehaus, A. Pecchia and G. Seifert

Dr Ben Hourahine: benjamin.hourahine@strath.ac.ukUniversity of Strathclyde

The Density Functional based Tight binding method is an approximate second�order expansion of the Kohn�Sham Density�Functional Theory (DFT) with respect to fluctuations in the charge density. This gives a transparent and parameter�freetechnique where all terms can be readily pre�calculated using DFT. Besides the usual "band structure" and short�rangerepulsive terms of tight�binding, the final approximate Kohn�Sham functional includes a Coulomb interaction between chargefluctuations. At large distances this accounts for long�range electrostatic forces while approximately including the exchange�correlation at short range. This allows DFTB to be successfully applied to problems, where deficiencies within the non�SCCstandard TB approach become obvious. Additionally, due to the explicit use of a basis set, charge distributions and molecularorbitals can be plotted.

In the last few years the DFTB method had been heavily expanded, closely following developments in DFT. Some recentextensions include:

* Spin polarisation (both collinear and two�component)* Finite electronic temperature (Mermin free energy)* Dispersion corrections (van der Waals interaction)* Car�Parrinello dynamics* Strong correlation treatment (LDA+U and pseudo�SIC)* Linear�response property calculations* Excited state (GW and time dependent DFTB)* Transport properties via Green functions techniques.* QM/MM coupling

The recent DFTB+ implementation allows molecular or periodic boundary conditions and also supports molecular dynamics inthe NVE, NVT and NPT ensembles.

http://www.dftb�plus.info/

24/ POSTER (16) Mr Cao Jie: Assessment of density functionals for the structure prediction of a Tyr�Glyconformer: Good performance of the M06�L functional

Assessment of density functionals for the structure predictionof a Tyr0Gly conformer: Good performance of the M060L

functionalCao Jie and Tanja van MourikMr Cao Jie: jc632@st�andrews.ac.uk

University of St Andrews

The routine B3LYP and MP2 methods do not always yield qualitatively correct structures for flexible organic systemscontaining pi systems, particularly when small to medium�sized basis sets are used. This is due to large basis setsuperposition errors in the MP2 calculations and the lack of dispersion in the B3LYP calculations. Here we study the ability ofseveral recently developed DFT methods to predict the conformation of a conformer of the Tyr�Gly dipeptide, for whichB3LYP/6�31+G(d) and MP2/6�31+G(d) geometry optimizations give strikingly different structures [Mol. Phys. 2006, 104,559�570]. B3LYP yields an open structure while MP2 yields a more folded structure. The Tyr�Gly geometry was optimizedwith fixed values (in the range from 3.0 to 8.0 A) of a distance that controls the degree of foldedness of the structure, usingthree levels of theory: B3LYP/6�31+G(d), M06�L/6�31G(d) and M05�2X/6�31+G(d). Afterwards, a series of DFT methods wereemployed to calculate the single�point energies and obtain the transition energy profiles. The local meta functional M06�L isfound to yield results in close agreement with the reference CCSD(T) profile.

27/1/1 ORAL PRES / POSTER (17) Dr Jos Koetsier: Rapid: giving computational science a friendly face

Rapid: giving computational science a friendly faceJ. Koetsier, A.R. Turner and J.I. van Hemert

Dr Jos Koetsier: jkoetsie@staffmail.ed.ac.ukUniversity of Edinburgh

Rapid is a unique approach to quickly designing and delivering web portal interfaces for applications that require largeamounts of computing resources or that need to run on specific servers. The approach consists of defining the resources,application use and user interface in one XML file. This file is then validated and translated directly into a live portlet that can beinserted into a portal container. The whole process can be performed without any conventional programming. Rapid providesall the necessary components for handling compute�jobs. It knows how to handle remote files stores, monitor jobs, validateinput, talk to Sun Grid Engine, Condor, PBS or just use a plain SSH connection.

Here we show a portal for teaching undergraduate chemistry students about structure and bonding of simple compoundsusing Gaussian 03. It was created by Andrew Turner using Rapid for the Rapid Chemistry Portals by Engaging Researchersproject. The whole process took him just several days.

28/ POSTER (18) Mr. Tobias Kraemer: Catalytic Nitrite Reduction by a CuNiR Model Complex – AComputational Study

Catalytic Nitrite Reduction by a CuNiR Model Complex – AComputational StudyT. Krämer*, J. E. McGrady

Mr. Tobias Kraemer: tobiask@chem.gla.ac.ukUniversity of Glasgow

Dissimilatory denitrification, which is carried out by the anaerobic respiratory pathway in bacteria and archaea, is an integralpart of the global nitrogen cycle.1 The committed step of the denitrification cascade is the single�electron reduction of nitrite tonitric oxide by the enzyme nitrite reductase (NiR). Crystal structures of copper nitrite reductase (CuNiR) reveal a homo�trimeric quaternary structure, where each domain contains type 1 and type 2 copper sites.2The actual catalysis takes place at the T2 site, while the T1 site is involved in the electron shuttle to provide the reductionequivalents. The catalytic mechanism of CuNiRs remains controversial due to the paradox between observed O�coordinationof nitrite and the N�coordination of metal�nitrosyls characterized chemically, as well as the exact function of conserved aminoacid residues near the catalytic centre, especially of a hydrophobic isoleucine (Ile257).Functional and structural model complexes of the type 2 copper site of CuNiR based on the triiminocyclohexane ligandsystem have been synthesized by Walton and co�workers.3Synthetic biomimetic complexes are useful to gain insight into the distinct chemical steps and electronic states being involvedin the catalytic cycle.We used quantum chemical calculations in order to understand the mechanistic details of nitrite reduction by the abovecomplexes on the electronic level. The calculations using the DFT approach, which have given good results on a similarcomplex system before4, point at the possibility that linkage isomerism of the copper�bound nitrite ligand is the key to the‘coordination change’ in going from nitrite to nitric oxide.

References1. I. S. MacPherson, M. E. P. Murphy, Cell. Mol. Life Sci., 2007, 64, 2887–2899.2. J. W. Godden, S. Turley, D. C. Teller, E. T. Adman, M. Y. Liu, W. J. Payne, J. LeGall, Science, 1991, 253, 438–442.3. A. K. Nairn, S.J. Archibald, R. Bhalla, C. J. Boxwell, A. C. Whitwood, P. H. Walton, Dalton Trans., 2006,1790–1795.4. E. Zueva, Paul H. Walton, John E. McGrady, Dalton Trans., 2006, 159–167.

31/ POSTER (19) Mrs Lorreta Lawton: Magnetic Interactions via Hydrogen Bonds and Anion/CationSubstitution effects on HB Interactions

Magnetic Interactions via Hydrogen Bonds and Anion/CationSubstitution effects on HB InteractionsL. Lawton, D. Middlemiss, L. Thomas and C. Wilson

Mrs Lorreta Lawton: lorrla@chem.gla.ac.ukUniversity of Glasgow

A series of model cubic structures have been studied in order to obtain magnetic coupling constants for metal centres linkedby hydrogen bonds of varying length. Hybrid functional calculations were performed on structures containing V, Ni or Cutransition metals linked by [FHF]�, [ClHCl]� or [FHCl]� ligands, in order to ascertain the dependence of coupling strength onexact exchange content, in the functional and on the structural parameters of hydrogen bond length and proton position.

The computational code CRYSTAL06 [1] was used to model these theoretical structures. This code allows for the use of boththe Hartree Fock and density functional theory approximations under periodic boundary conditions, and also for the mixedhybrid�exchange calculations that have been shown to yield accurate coupling constants in similar cubic structures [2].

This investigation has also been extended to experimental structural studies in which the effects of cation and anionsubstitution in the starting materials on the structural packing of a number of organometallic compounds are underexamination. Findings from both the computational and experimental investigations will be presented.

[1] R. Saunders, R. Dovesi, C. Roetti, R. Orlando, C.M. Zicovich�Wilson, N.M. Harrison, K. Doll, B. Civalleri, I.J. Bush, Ph.D’Arco, M. Llunell, CRYSTAL 2006 User’s Manual.

[2] D. S. Middlemiss, C. C. Wilson, A. Harrison and L. M. Lawton, to be published.

32/ POSTER (20) Dr Tomas Lebl: NMR and computational study of conformational behaviour of medium�sized ring triones

NMR and computational study of conformational behaviour ofmedium0sized ring triones

T. Lebl, A. M. Jones, G. Liu, A. M. Z. Slawin, D. Philp and N. J. WestwoodDr Tomas Lebl: tl12@st�and.ac.uk

School of Chemistry, University of St Andrews

For series of medium�sized ring triones synthesised by the oxidative fragmentation of bicyclic ring systems interestingdynamic behaviour was observed by NMR spectroscopy in solution. Combination of variable temperature NMR, totallineshape analysis, X�ray crystallography and molecular modelling revealed two dynamic processes associated with axialchirality of the medium sized�ring and restricted rotation of chlorophenyl substituent. Elucidation of dynamic behaviour helpedto understand the mechanism of oxidative fragmentation used to prepare the triones.

33/ POSTER (21) Mr. Sanliang Ling: Interactions of Hydrogen and Methanol with the MO3 (M=W or Re)Surfaces: The Effect of Epitaxial Interface on the Reactivity

Interactions of Hydrogen and Methanol with the MO3 (M=W orRe) Surfaces: The Effect of Epitaxial Interface on the Reactivity

Sanliang Ling, Donghai Mei, Maciej GutowskiMr. Sanliang Ling: SL160@hw.ac.uk

Heriot�Watt University

Conductive and narrow bandgap transition metal oxides have been used for many years in various industrial applications.Tungsten trioxide (WO3) and rhenium trioxide (ReO3) are widely used as catalysts and support materials in heterogeneouscatalysis and photocatalysis. For example, methanol was found to be molecularly adsorbed to the Lewis acid sites of oxidizedWO3(001) surface while dissociatively adsorbed to the Brønsted base sites of reduced WO3(001) surface. High catalyticactivities and selectivities for the oxidation of methanol were also found on supported ReOx surfaces. With the advances inmolecular beam epitaxy technology, new types of interfacial structures that are built by two structurally similar transition metaloxides provide promising enhanced catalytic performance due to the formation of new band structures near the Fermi level. Inthe present study, the reactivities of hydrogen and methanol on the interfacial WO3/ReO3 and ReO3/WO3 structures wereexplored and compared with analogous reactivities on the surfaces of pure WO3 and ReO3. The results of our densityfunctional theory calculations indicate that the reactivities of the conductive and semiconductive transition metal oxides mightbe tuned by making overlayer�like interfacial structures. The possibilities for improved and optimal catalytic activity should befurther explored by theoretical and experimental studies in the future.

35/ POSTER (22) Mr Dario Marrocchelli: The construction of a reliable potential for GeO2 from first�principles

The construction of a reliable potential for GeO2 from first0principles

D Marrocchelli, M. Salanne, P.A. Madden, C. Simon and P. TurqMr Dario Marrocchelli: D.Marrocchelli@sms.ed.ac.uk

University of Edinburgh

In the vitreous and liquid states, at ambient pressure, germania (GeO2) (a close structural analog of silica (SiO2)) forms atetrahedrally�coordinated three�dimensional network [1]. GeO2 is used in several fields, mainly related to optical technologies.For example, a mixture of SiO2 and GeO2 allows precise control of the refractive index in optical fibres and waveguides. It isof interest to develop simulation methods to allow a detailed examination of the local structure in such mixtures and to predictthe infrared spectrum, since this determines the long�wavelength limit for their use as optical fibres.In the past few years, a lot of effort has been done to study this material by means of both first�principles molecular dynamics(FPMD) [1] and classical molecular dynamics (MD) simulations [2], using pair�wise additive potentials. Although thesetechniques were successful in some cases, they both present some important drawbacks. FPMD simulations, in fact, thoughsuccessful at reproducing the structural and optical properties of this system are computationally very expensive andtherefore unsuitable for the system sizes and timescales usually required for the study of glassy materials. Classicalmolecular dynamics simulations, on the other hand, are much faster and can be easily used to study systems with manyhundreds of atoms on the nanosecond scale but they usually lack accuracy and need different sets of parameters torepresent different properties.In this work we describe the parameterization of a new classical MD interaction potential for GeO2, using techniques we havedeveloped for halides and oxides, which is entirely based on first�principles, electronic structure calculations. In order toprovide an accurate, transferable description of the interactions, these potentials include dipole polarization effects and theions carry full valence charges. The obtained potential is able to reproduce all the studied properties (structural, dynamicaland vibrational) to a high degree of precision with a single set of parameters. The agreement with the experimental data iscomparable with the one obtained from FPMD calculations, although our simulations are much faster. We are currently usingthese potentials to study the effects of pressure on glassy GeO2 and to study SiO2�GeO2 mixtures.[1] L. Giacomazzi, P. Umari, and A. Pasquarello, Phys. Rev. Lett. 95 (7), 075505 (2005).[2] M. Micoulaut, Y. Guissani, and B. Guillot, Phys. Rev. E 73, 031504 (2006).

39/ POSTER (23) Mr David McKay: Computational Studies of the Isomerisation of Nido� and Closo� 12�vertex Carboranes

Computational Studies of the Isomerisation of Nido0 andCloso0 120vertex Carboranes

D. McKay, S. A. Macgregor and A. J. WelchMr David McKay: dm172@hw.ac.uk

Heriot�Watt University

The production of supraicosahedral carboranes requires the reduction of a closo 12�vertex species to anido fragment followed by capitation. We have used computational methods to study the reduction ofcloso�C2B10H12 species. The reduction of para�carborane is particularly complex and produces fivedifferent nido dianionic minima. We present the full characterisation of the initial products of reductionand the subsequent isomerisation pathways to all five nido species.

These results agree with experimental studies which have shown that reduction and capitation of para�carborane produces 13�vertex ruthenacarboranes derived from these nido intermediates.1Additional computational studies show the 2e reduction of ortho� and meta�carborane produce [7,9�nido�C2B10H12]

2�, in agreement with experimental studies.2 Reoxidation then gives a new species shown tobe an intermediate in a new low energy route for isomerisation of ortho� to meta�carborane. Amechanism supported by the formation of sterically crowded ortho�carboranes by reduction andsubsequent oxidation of a meta�carborane with bulky C substituents.3

1 S. Zlatogorsky, M. J. Edie, D. Ellis, S. Erhardt, M. E. Lopez, S. A. Macgregor, G. M. Rosair and A. J.Welch, Angew. Chem.�Int. Edit., 2007, 46, 6706�6709.

2 a) G. B. Dunks, R. J. Wiersema and M. F. Hawthorne, J. Am. Chem. Soc., 1973, 95, 3174�3179; b) L. I.Zakharkin and V. N. Kalinin, Dokl. Akad. Nauk SSSR, 1966, 169, 590.

3 B. W. Hutton, F. MacIntosh, D. Ellis, F. Herisse, S. A. Macgregor, D. McKay, V. Petrie�Armstrong, G. M.Rosair, D. S. Perekalin, H. Tricas and A. J. Welch, Chem. Commun., 2008, 5345�5347.

41/ POSTER (24) Mr Russell McKinlay: Theoretical Studies of One and Two�Photon AbsorptionSpectroscopy of Fe(CO)5 and Potential Energy Surfaces for Photodissociation

THEORETICAL STUDIES OF ONE AND TWO'PHOTON ABSORPTIONSPECTROSCOPY OF Fe(CO)5 AND POTENTIAL ENERGY SURFACES FOR

PHOTODISSOCIATIONRussell G. Mckinlay and Martin J. Paterson

School of Engineering and Physical Sciences, Heriot Watt University, Edinburgh, EH14 4ASFe(CO)5 is a paradigm complex which has many practical applications and been the subject of

intense study over the years. Particular interest has been paid to the photochemistry of this complex andother metal carbonyls as they are perhaps the most photoreactive transition metal compounds, and can beused to demonstrate many types of known electronic excited states. Indeed, their rather simplisticstructures belie rather complicated vibronic coupling induced phenomena [1], which is only nowbeginning to be understood due to advances in spectroscopic and theoretical methods. One part of thisproblem is the assignment of the electronic spectra of Fe(CO)5. Historically the experimental spectrum

has been poorly resolved due to a high density of vibronic states of different character stronglyoverlapping. Interpretation has been somewhat controversial, with many different theoretical methodshaving being applied. We present our assessment of both one and two�photon electronic absorptionspectrums for Fe(CO)5 by theoretical investigation using a hierarchy of coupled cluster response theory

methods, CC2, CCSD and CCR(3) in all electron atomic natural orbital bases. These powerful methodstreat all excited states in a balanced manner.

After photodissociation of the parent Fe(CO)5 vibrationally hot Fe(CO)4 is generated on a sub�

picosecond timescale. Time�resolved ultrafast spectroscopy has inferred a non�adiabatic radiationlessdecay channel for the photoproduct in the singlet electronic manifold. We present results of multi�configurational complete�active space self�consistent�field (CASSCF) calculations of the multi�statepotential energy surfaces including triply� and doubly�degenerate Jahn�Teller geometries responsible forthe ultrafast nature of the decay and subsequent vibrational coherence observed in the photoproduct.

[1]. S. A. Trushin, W. Fuss, K. L. Kompa and W. E. Schmid, J. Phys. Chem. A. 2000, 104, 1997�2006.

45/ POSTER (25) Mr Robert Noble�Eddy: The hunt for (the structure of) dibenzylsulfone

The hunt for (the structure of) dibenzylsulfoneR. Noble�Eddy and S. Masters

Mr Robert Noble�Eddy: r.noble�eddy@ed.ac.ukUniversity of Edinburgh

Current work in the research area of gas electron diffraction (GED) is focussed towards determining the molecular structuresof reactive species. One favourable target for study by GED is the benzyl radical, an industrially important molecule whosegaseous structure has not been analysed. We chose dibenzylsulfone [(PhCH2)2SO2, DBS] as a suitable precursor to thisradical. The products of pyrolysis at ~1000 K are known to be the benzyl radical and SO2, the structure of which is wellknown experimentally and computationally. This allows the pattern to be analysed solely for the radical. As in all experiments,we wished to analyse the structure of the precursor in a separate experiment to ensure that it could be accounted for shouldclean dissociation not occur under the conditions of the experiments.

What should have been a straightforward analysis has turned into a conformer hunt. GED alone cannot tell us theconformational make�up of DBS; does it exist as 1 or multiple conformations? A series of 1D scans around φO�S�C�C andφS�C�C�C located the obvious C2v and C1 structures, which simply did not fit our diffraction patterns and were subsequentlyfound at MP2 level to possess imaginary frequencies. We have found conformers that are maxima on the potential energysurface at lower energies to the two initial conformers, and minima that are higher in energy!

Ideally a 4D potential energy scan would be conducted a high level to fully explore the conformational space, but evenscanning in 15° steps would require 72,000 geometry optimisations! This is prohibitively expensive, even using HF, thus theonly option is to use a molecular mechanics method, but as we have found that HF and MP2 don’t agree, will this be accurateenough?

The 4D scan is currently underway. This poster will explain more about our pyrolysis experiments, and the epic struggle todetermine the molecular structure of dibenzylsulfone.

46/ POSTER (26) Mr. Benjamin PEIGNE: Spin delocalization into Fe(L�S)2Mo and MoFe3S4 cubanessystems

Spin delocalization into Fe(E0S)2Mo and MoFe3S4 cubanessystems

B. Peigné, W.M.C. Sameera, G. Aullón, and J. McGradyMr. Benjamin PEIGNE: benjamin.peigne@qi.ub.es

Universitat de Barcelona

The active center of the nitrogenase enzyme, the FeMo�cofactor, is known to transform atmospheric nitrogen into ammonia,but the reaction pathway remains unknown. In order to understand it, we have been studying the electronic structure of [X2Fe(_�S)2MoS2]2� bimetallic model systems (1), with X = Cl, SH, SCH3, SPh and S5. The metal environment is tetrahedral andthe electronic distribution can be formulated as FeIIIMoV or FeIIMoIV. Our calculations suggest that the FeIIMoIV state isenergetically favored. We have also considered the electronic structures of the tetrametallic species [Cl3MoFe3S4Cl3]4� (2),where the molybdenum atom is in an octahedral environment, but the same questions regarding the localization of unpairedelectrons arise. In this case, a MoIVFeIIIFeII2 state is most stable.The calculations are performed with the Gaussian 03 code using initial guess functions generated with the Jaguar 6.5 code,and ORCA calculations in order to get Mössbauer properties (3) that could be compared with experimental data.

Bibliographic references:

(1) D. Coucouvanis, N.C. Baenziger, E.D. Simhon, P. Stremple, and D.Swenson, JACS, 102, 1730, 1980.(2) D.V. Fomitchev, C.C. McLauchlan, and R.H. Holm, Inorg. Chem., 41, 958, 2002.(3) M. Römelt, S. Ye, and F. Neese, Inorg. Chem., 48, 784, 2009.D. Coucouvanis, Acc. Chem. Res., 14, 201, 1981.

47/ POSTER (27) Mr Julien Panetier: Computational Studies of Intermolecular Aromatic C�F BondActivation by a Rhodium(I) Silyl Complex

Computational Studies of Intermolecular Aromatic C�F Bond Activation by a Rhodium(I) SilylComplex

Julien A. Panetier and Stuart A. Macgregor

School of Engineering and Physical Sciences, Heriot�Watt University, Edinburgh, EH14 4AS

The activation of C�F bonds by transition metals centres has an important role in the functionalizationof polyfluorinated organic molecules in the chemical and pharmaceutical industries. Indeed selectivedefluorination is easier than selective fluorination.

In 1994, Aizenberg and Milstein described the homogeneous catalytic activation of aromatic C�F bondsby a rhodium(I) silyl complex under mild conditions.1 This catalytic reaction proceeds with thesubstitution of fluorine by hydrogen (hydrodefluorination) using hexafluorobenzene and hydrosilanes, asshown below.

Density functional theory calculations have been carried out to model the reaction of C6F6 with

[RhSiR3(PMe3)3]. The reaction occurs via initial phosphine dissociation followed by an oxidative

addition (metal insertion into C�F) and reductive elimination (formation of Si�F bond). In addition,calculations showed that for pentafluorobenzene C�F activation at the 4 position was favoured over C�Hactivation.

1. M. Aizenberg and D. Milstein, Science, 1994, 265, 359�361.

48/ POSTER (28) Mr Grant Paterson: Synergy between Experiment and Theory: Exploring the CollisionDynamics of OH + Simple Partners

Synergy between Experiment and Theory: Exploring theCollision Dynamics of OH + Simple PartnersG.Paterson, S. Marinakis, M. L. Costen, K. G. McKendrick

Mr Grant Paterson: g.paterson@hw.ac.ukHeriot�Watt University

Free radicals play a crucial role in many gas�phase environments, particularly in combustion and the atmosphere. Both elasticand inelastic collisions of such species are a vital component of the chemistry, controlling, for example, the dissipation ofenergy released in exothermic reactions. They are also central to the optical sensing methods often used in these contexts,affecting the relationship between signal intensities and number densities, and also the widths and shapes of spectral lines.Experimental measurement of every significant process is impossible. It is therefore necessary to construct accuratePotential Energy Surfaces (PES) and perform dynamical scattering calculations instead. Experimental testing of thesetheoretical predictions is an essential part of their development.

We have developed a state�of�the�art laser�based experimental technique, called Polarisation Spectroscopy (PS), to study thefundamental dynamics of these inelastic collisions and test these theoretical predictions. We have studied the collisions of theOH radical (important in combustion and atmospheric chemistry) with a range of atomic and molecular colliders (He, Ar, Xe,N2 and O2). The PS technique generates a polarization of the rotational angular momentum vector, j, and monitors thecollisional evolution of the prepared polarization. The rate of loss of the PS signal depends on the rate of population transfer,and uniquely, the elastic depolarization. This classically represents the ‘tilting’ of j in space as a result of collisions, withretention of its magnitude.

We compare our experimental results to close�coupled quantum scattering calculations on the most recent ab initio PES (OH�He, OH�Ar and OH�Xe). The calculations include both rotational state and fine�structure changing collisions, and as a result ofa recent development of the quantum scattering codes, elastic depolarization. OH(X)�He collisions are found to be dominatedby the repulsive core of the PES for all processes, consistent with our experimental results. OH(X)�Ar and OH(X)�Xeexperiment and calculation reveal a subtle balance between population transfer and depolarization, illustrating the very highsensitivity of this vector measurement to the fine details of the attractive parts of the PES.

We will also present intriguing differences in PS experiments in collisions of OH(X) with N2 and O2. Their obvious kinematicsimilarity makes these an ideal test of the effect of varying the PES. Surprisingly N2 is found to depolarize OH(X) significantlyfaster than O2, at odds with simple predictions based on the latest literature PES.

55/ POSTER (29) Mr. Anthony Reilly: Understanding the effects of anharmonic thermal motion

Understanding the effects of anharmonic thermal motionA.M. Reilly, D.A. Wann, C.A. Morrison and D.W.H. Rankin

Mr. Anthony Reilly: anthony.reilly@ed.ac.ukUniversity of Edinburgh

The equilibrium structure of a crystal represents the system in a theoretical vibrationless state at the absolute minimum of itspotential�energy surface. Such structures can be compared directly between different phases and polymorphs and withtheoretical calculations. Structures determined using X�ray and neutron�diffraction experiments are time�averaged over all ofthe molecular vibrations occurring in the crystal. If these motions are anharmonic or curvilinear then the time�averaged andequilibrium structures will differ. This work outlines a new method that uses molecular dynamics simulations to estimate thedifferences between time�averaged and equilibrium structures. The application of the method to the crystal structures ofnitromethane and benzophenone will be detailed.

58/ POSTER (30) Dr Patricia Richardson: The EaStCHEM Research Computing Facility

The EaStCHEM Research Computing FacilityP. Richardson

Dr Patricia Richardson: patricia.richardson@ed.ac.ukUniversity of Edinburgh

Computational chemistry techniques can be powerful tools in the arsenal of an experimental scientists, both as aids tounderstanding observed phenomena and as predictive tools of likely behaviour and reactivity. Unfortunately, manyexperimental scientists lack the necessary skills and experience to independently exploit computational chemistry methods intheir research. The EaStCHEM Research Computing Facility (RCF) was set up in late 2006 with the aim of overcoming theseproblems by providing an in�house service for researchers, within EaStCHEM, wishing to utilise computational chemistry. TheRCF provides access to dedicated hardware, software and support, in the form of training and consultancy, in order to enableresearchers to rapidly and successfully employ computational methods in their own research.

60/ POSTER (31) Ms Evdokiya Salamanova: Molecular dynamics simulations on the halogenase PrnA

Molecular dynamics simulations on the halogenase PrnAE. Salamanova and H. M. Senn

Ms Evdokiya Salamanova: eddie@chem.gla.ac.ukUniversity of Glasgow

Molecular dynamics simulations on the halogenase PrnAEvdokiya Salamanova, Dr Hans Martin SennWestCHEM and Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, Scotland, UK

PrnA is a regioselective halogenating enzyme, which catalyses the first step of the biosynthesis of the natural antifungal agentpyrrolnitrin. It belongs to the family of the flavin�dependent halogenases and it is involved in the chlorination of tryptophan to 7�chlorotryptophan. The enzyme is produced by the bacterium Pseudomonas fluorescens and it is a dimer in solution1. It canexist in two forms: protonated (LYP) and non�protonated (LYN), depending on the protonation of residue lysine 79. Eachmonomer of the enzyme binds flavin adenine dinucleotide (FAD) co�factor, the tryptophan substrate and chloride. Thereduced FAD (FADH2) reacts with oxygen forming hydroperoxyflavin (FADHOOH).We performed classical molecular dynamics simulations on the PrnA monomer in the two possible forms: LYP and LYN withFADHOOH bound, using GROMACS 3.3.3 with the AMBER03 force field. The ligands were built as non�standard residueswith GAFF (general AMBER force field) and their charges were obtained by fitting to the electrostatic potentials, calculatedusing B3LYP/cc�pVTZ//HF/6�31G** quantum mechanical methods2. We performed 1ns equilibration and 6ns production runfor both systems. We will report the RMSD values of the two systems and compare the results.

References:

1. Dong, C., Flecks, S., Unversucht, S., Haupt, C., van Peé, K. H., Naismith, J. H., Science, 2005, 309, 2216�2219.2. Y. Duan; C. Wu; S. Chowdhury; M. Lee; G. Xiong; W. Zhang; R. Yang; P. Cieplak; R. Luo; T. Lee; J. Caldwell; J. Wang; P.Kollman, J. Comput. Chem. , 2003, 24, 1999�2012.

61/ POSTER (32) Mr Chamil Sameera: Biomimetic water oxidation: some clues from computationalchemistry

Biomimetic water oxidation: some clues from computationalchemistry

W. M. C. Sameera and John E. McGradyMr Chamil Sameera: sameera@chem.gla.ac.uk

University of Glasgow

The splitting of water by photosynthesis organisms is one of the most remarkable phenomena of nature, where the oxygenevolving centre (OEC), a tetra manganese cluster found in the Photosystem II, is central to this process[1]. However, detailedchemical steps involved in the oxygen evolution and precisely how such highly active species avoid oxidative damage to thesurrounding protein environment remain a mystery. In developing our understanding of photosynthetic water oxidation,synthetic oxygen evolving complexes, small molecular mimics of the OEC, are very useful in exploring cluster featuringmultiple electronic states and detailed chemical steps of the water oxidation process. We used quantum chemical calculations,specifically density functional theory (DFT), to explore biomimetic Mn�based oxygen evolving systems synthesized by Narutaand co�workers[2] and McKenzie and co�workers[3]. DFT calculation on these systems suggested that the ‘metal�oxylcharacter’ [Mn(IV)�O.+], as distinct from metal�oxo form [Mn(V)=O], is the common denominator for the O�O bond formation.In cases where the oxyl radical character is ‘masked’ in the ground state by electron transfer from either the metal or theporphyrin co�ligand, the interaction between oxidant and substrate is repulsive at large separations, only becoming attractivewhen the incoming nucleophile approaches close enough to drive an electron out of oxide pπ manifold, thereby ‘unmasking’the oxyl radical[4]. The active role of substrate in unmasking the oxyl radical character of the Mn(V)=O unit offers the potentialfor discrimination that is one of the defining features of the oxygen evolving centre, and may represent a general frameworkfor understanding structure function relationships in water oxidation catalysts.

References1. K. N. Ferreira, T. M. Iverson, K. Maghlaoui, J. Barber, S. Iwata, Science 2004, 303, 1831.2. (a) Y. Shimazaki, N. Nagano, H. Takesue, B. H. Ye, F. Tani, Y. Naruta Angew. Chem. 2004, 116, 100. (b) Y .Naruta, M.Sasayama, T. Sasaki, Angew. Chem. Int. Ed. Engl. 1994, 33, 1839.3. (a) A. K. Poulsen, A. Rompel, C. J. McKenzie, Angew. Chem. Int. Ed. 2005, 44, 6916. (b) C. Baffert, M. N. Collomb, A.Deronzier, S. K Knudsen, J. M. Latour, K. H. Lund, C. J. McKenzie, M. Mortensen, L. P. Nielsen, N. Thorup, DaltonTrans.2003,1765.4. (a) W. M. C. Sameera, J. E. McGrady, Dalton Trans. 2008, 6141. (b) A. E. Anastasi, P. H. Walton, J. R. L. Smith, W. M. C.Sameera, J. E. McGrady, Inorg. Chim. Acta 2008, 361, 1079.

62/ POSTER (33) Dr. Jörg Saßmannshausen: From DFT to spectroscopy and back: The use of bothtechniques to unearth active compounds in homogeneous catalysis

From DFT to spectroscopy and back: The use of bothtechniques to unearth active compounds in homogeneous

catalysisJ. Saßmannshausen

Dr. Jörg Saßmannshausen: jorg.sassmannshausen@strath.ac.ukUniversity of Strathclyde

For some time now we are using the combination of DFT calculations and spectroscopy, in particular NMR and IR, as a workhorse for the investigation of active species in homogeneous catalysis. This combination has proved to be very fruitful. Thetalk will present selected examples. For the combination of DFT and NMR, we present work in the area of group 4metallocene catalysts. The area of DFT and IR will be represented by a Fe pincer compound.

64/ POSTER (34) Mr Lukasz Serafin: Chemical bonding properties in substituted silicon hydride isomers

Chemical bonding properties in substituted silicon hydrideisomers

L. Serafin, T. van Mourik and M. M. LawMr Lukasz Serafin: ls567@st�andrews.ac.uk

University of St. Andrews

The coupled – cluster singles, doubles ( triples) [CCSD(T)] level of theory with Dunning’s correlation consistent basis set oftriple zeta quality with diffuse functions (aug�cc�pVTZ) has been carried out to obtain geometric and vibrational frequencyproperties for different structures of Si2HX (X= Li, F, Cl) and Si2H2. Using NBO calculations it is possible to clearly describeLewis structures of the obtained Si2HX and Si2H2 forms. The NBO calculations were done with the MP2 method andDunning’s correlation consistent basis set of quadruple – zeta quality (cc�pVQZ). The dibridged (SiHXSi) structures of the Cl(Si�Si single bonded) and Li (Si�Si double bonded) species have the lowest energy followed for Cl by the monobridged (XSiHSi– double bonded with H atom bridged cE= 4.38 kcal/mol), the vinylidene (HXSiSi – triple bonded cE = 8.01 kcal/mol) and thetrans (HSiSiX – double bonded cE = 11.79 kcal/mol). In the case of Li the difference between the lowest dibridged form andthe monobridged (HSiXSi – double bonded with Li bridged) isomer is 4.12 kcal/mol and for the monobridged form (XSiHSi�triplebonded with H atom bridged) is 8.91 kcal/mol. The case of the F species is slightly different: the monobridged structure(XSiHSi� double bonded with H atom bridged) has the lowest energy, followed by the vinylidene isomer (HXSiSi – doublebonded) with cE = 3.59 kcal/mol, the trans (HSiSiX – triple bonded) with cE = 7.30 kcal/mol and the dibridged (SiHXSi) formwith cE= 7.53 kcal/mol.

65/ POSTER (35) Miss Lynsey Shepherd: Fast Proton Transport through Proteins via Internal Water Wires

Fast Proton Transport through Proteins via Internal WaterWires

L.M.S.Shepherd and C.A.MorrisonMiss Lynsey Shepherd: s0344412@sms.ed.ac.uk

University of Edinburgh

Proton transport (PT) across membranes is known to occur via hydrogen bonded chains of water molecules housed withinmembrane spanning proteins. Modelling these trans�membrane proteins at the full atomistic quantum mechanical level liesbeyond the capabilities of current computational techniques, necessitating the use of simplified models. Ab initio MDsimulations on a polyglycine helix and water wire expressed under periodic boundary conditions has created a channel thatsupports PT up to a distance of 9 Å and is consistent with the classical Grotthuss mechanism. The addition of an excessproton to a chain of water molecules induces water cooperativity and long range order. The role of helical movement ishighlighted as crucial for proton transport: too little and the transfer step becomes a local shuttling event between neighboringwater molecules, too much and the helical groove is lost, which results in the loss of long�range water co�operativity withdiffusion becoming the dominant effect.

66/ POSTER (36) Dr. Nicolas Sieffert: Non�Covalent Interactions in a Transition�Metal TriphenylphosphineComplex: a Density Functional Case Study

Non0Covalent Interactions in a Transition0MetalTriphenylphosphine Complex: a Density Functional Case Study

N. Sieffert, M. Bühl*Dr. Nicolas Sieffert: nss10@st�andrews.ac.uk

University of St. Andrews

The binding enthalpy of a triphenylphosphine ligand in Ru(CO)Cl(PPh3)3(CH=CHPh) is studied with “standard” (BP86 andB3LYP), dispersion�corrected (B3LYP�D and B97�D), and highly parametrized (M05 and M06 series) density functionals. Anappropriate treatment of non�covalent interactions is mandatory as these turn out to account for a large fraction of the metal�ligand interaction energy. Among the tested methods, B97�D and the M06 series of functionals best reproduce theexperimental binding enthalpy value of Sponsler et al. (Inorg. Chem. 2007, 46, 61).

71/ POSTER (37) Dr Derek Wann: A molecular dynamics approach to equilibrium structures in gases andcrystals

A molecular dynamics approach to equilibrium structures ingases and crystals

Derek A. Wann, Anthony M. Reilly, and David W. H. RankinDr Derek Wann: derek.wann@ed.ac.uk

University of Edinburgh

In order for experimental and theoretical structures to be directly compared it is often desirable to “correct” the experimentalstructures for the effects of vibrations. We have developed a method that uses state�of�the�art molecular dynamicssimulations to provide the necessary corrections. Examples will be given of their use in determining both gas�phasestructures of silsesquioxanes and the crystal structure of nitromethane.Determining equilibrium crystal structures is more desirable than ever because of recent developments in periodic solid�statecomputational methods. We have outlined a method that uses molecular dynamics (MD) simulations in conjunction withperiodic boundary conditions to correct the positions of atoms in crystals for the effects of vibrational averaging.[1] Thecorrections have been achieved by taking the differences between atomic positions from a geometry optimisation and thoseaverage positions sampled during the MD simulation.For structures in the gas phase corrections have traditionally been obtained from calculated force constants using programssuch as ASYM[2] and SHRINK.[3] However, for molecules with large�amplitude and/or low�frequency modes of vibration, thisapproach can fail. This was shown to be the case for the gas�phase electron diffraction (GED) determination of the sodiumchloride dimer structure.[4] The MD method has also been successfully applied to the determination of gas�phase equilibriumstructures. In this case a single molecule is placed in a large cell. By taking the differences between optimised interatomicdistances and those average distances yielded by the MD simulations, corrections for use in GED refinements can beobtained. These corrections are similar in value to those obtained by SHRINK for cases where SHRINK is expected to becorrect. However, this method also gives reasonable values in situations where more traditional methods of calculatingcorrections have significantly over� or underestimated the values. This will be demonstrated by reference to the determinationof the structures of silsesquioxanes.[5]1. A. M. Reilly, D. A. Wann, C. A. Morrison and D. W. H. Rankin. Chem. Phys. Lett., 2007, 448, 61.2. L. Hedberg and I. M. Mills, J. Mol. Spectrosc., 2000, 203, 82.3. V. A. Sipachev, J. Mol. Struct. (THEOCHEM), 1985, 22, 143.4. P. D. McCaffrey, R. J. Mawhorter, A. R. Turner, P. T. Brain and D. W. H. Rankin. J. Phys. Chem. A, 2007, 111, 6103.5. D. A. Wann, R. J. Less, F. Rataboul, P. D. McCaffrey, A. M. Reilly, H. E. Robertson, P. D. Lickiss and D. W. H. Rankin,Organometallics, 2008, 27, 4183.

73/ POSTER (38) Mr Alexander Whiteside: Computational measures of electronegativity for groups andmolecular ions

Computational measures of electronegativity for groups andmolecular ions

A. Whiteside, M. Gutowski, S. Xantheas, S. Eustis, K. BowenMr Alexander Whiteside: aw95@hw.ac.uk

Heriot Watt University

The history of the quantitative electronegativity of the atoms is briefly discussed, and its usefulness in making chemicalpredictions is emphasised. The theoretical basis for obtaining the electronegativity of groups or molecular ions is thendiscussed, and computational methods are used to calculate the electronegativity of the ammonium radical. Predictions madeusing this electronegativity are compared to available experimental data. Some recent work on the systems NH3HX where X= halogen is also discussed.

75/ POSTER (39) Dr Ekaterina Zueva: Electronic structure and magnetic properties of a trigonal prismaticCuII6 cluster

Electronic structure and magnetic properties of a trigonalprismatic CuII6 cluster

E. M. Zueva, M. M. Petrova, R. Herchel, Z. Trávníček, R. G. Raptis, L. Mathivathananand J. E. McGrady

Dr Ekaterina Zueva: zueva_ekaterina@mail.ruUniversity of Glasgow

A combination of detailed magnetic susceptibility studies and electronic�structure analysis using broken�symmetry DFT isused to explore the electronic structure of a trigonal prismatic CuII6 cluster. The presence of six paramagnetic metal centreswith S = 1/2 gives rise to a maximum multiplicity of S = 3 and a total of 31 broken�symmetry states with MS < 3. Computeddifferences in energy between the high�spin and broken�symmetry states are expressed in terms of the 15 distinctHeisenberg exchange coupling parameters, Jij, and the equations are solved by a least�squares fitting procedure. Byinspection of the errors introduced by progressive symmetrisation of the Hamiltonian to reduce the number of independent Jij,we arrive at a minimal model containing only four distint Jij (three intra� and one inter�triangular). The computed values proveto be in good agreement with the corresponding values obtained from fitting of the magnetic susceptibility data in thetemperature regime above 10 K. The inclusion of antisymmetric exchange is necessary to fit the field� and temperaturedependence of the magnetisation at very low temperature.

76/ POSTER (40) Ms Justyna Zurek: Computational Studies of Vibronic Effects in Inorganic Chemistry:Photostereochemistry of (BQA)PtMe2I, and the Pseudo�Jahn�Teller Effect in Mo2(DXylF)2(O2CCH3)2(P2�O)2

Computational Studies of Vibronic Effects in Inorganic Chemistry: Photostereochemistry of(BQA)PtMe2I, and the Pseudo'Jahn'Teller Effect in Mo2(DXylF)2(O2CCH3)2(m2'O)2

Justyna Zurek and Martin J. PatersonSchool of Engineering and Physical Sciences, Heriot(Watt University, Edinburgh EH14 4ASComputational studies have been carried out on two large inorganic systems which each show

important vibronic coupling effects. The bis(8�quinolinyl)amide (BQA) derived platinum complex,(BQA)PtMe2I has been experimentally found to undergo irreversible photostereochemical transformation

from the mer form to the fac form upon exposure to visible light1. We have studied the electronicspectroscopy and photochemistry of this system using time�dependent density functional theory,configuration interaction, and multi�configurational electronic structure methodologies. The electronicabsorption is mainly localised on the pincer ligand, which drives the photochemical reaction in theexcited state (changing the pyramidalisation of the linking nitrogen atom), and the system can decay tothe ground electronic state on the fac side of the reaction via a conical intersection between the groundstate and a locally excited (BQA) state.

Another system investigated was Mo2(DXylF)2(O2CCH3)2(m2�O)2 complex (DXylF = N,N’�di

(2,6�xylylformamidine)). The crystal structure of the central bi�metallic motif was found to be of C2hsymmetry rather then the expected D2h and a possible rationalisation was a pseudo�Jahn�Teller

interaction.2 We have investigated both the target system and a model complex; our complete�activespace self�consistent�field (CASSCF) results indicate a vibronic coupling between the closed�shell groundelectronic state and a low�lying pd* state allows for the non�totally symmetric distortion.1. Harkins, S. B.; Peters, J. C., Unexpected photoisomerization of a pincer�type amido ligand leads to facial coordination at Pt(IV). Inorg. Chem. 2006, 45 (11), 4316�4318.2. Cotton, F. A.; Daniels, L. M.; Murillo, C. A.; Slaton, J. G., A pseudo�Jahn�Teller distortion in an Mo�2(mu(2)�O)(2) ringhaving the shortest Mo�IV�Mo�IV double bond. J. Am. Chem. Soc. 2002, 124 (12), 2878�2879.

77/ POSTER (41) Dr Tanja van Mourik: Assessment of density functionals for intramolecular dispersion�rich interactions

Assessment of density functionals for intramoleculardispersion0rich interactions

Tanja van MourikDr Tanja van Mourik: tanja.vanmourik@st�andrews.ac.uk

University of St Andrews

A range of density functional theory methods, including conventional hybrid and meta�hybrid functionals, a double�hybridfunctional, and DFT�D (DFT augmented with an empirical dispersion term) are assessed for their ability to describe threedifferent conformations of the Tyr�Gly dipeptide, which are particularly sensitive to intramolecular dispersion and basis setsuperposition error. The results are compared to an estimated CCSD(T)/CBS reference profile. It is shown that the bestperformance is delivered by the most elaborate density functional theory model employed, a double hybrid functionalaugmented with a dispersion term: mPW2�PLYP�D. Only M06�2X and mPW2�PLYP�D predict the correct order of stability ofthe three minima.