Post on 25-Aug-2020
Physics of Condensed Matter I
Faculty of Physics UW
Jacek.Szczytko@fuw.edu.pl
1100-4INZ`PC
Molecules 3
H2+ ion
Trial functions of the hydrogen atom (variational method)
1s 1s
1su+
1sg+
EatEat
e+
e-P. Atkins
2015-11-27 2
Molecules
Ξ¨+ = π+ 1π π΄ + 1π π΅
Ξ¨β = πβ 1π π΄ β 1π π΅
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H2+ ion
Trial functions of the hydrogen atom (variational method)
1s 1s
1su+
1sg+
EatEat
e+
e-
2015-11-27 3
Molecules
Ξ¨+ = π+ 1π π΄ + 1π π΅
Ξ¨β = πβ 1π π΄ β 1π π΅
P. Atkins
Atkins, Fridman Molecular QM
H2+ ion
Trial functions of the hydrogen atom (variational method)
1s 1s
1su+
1sg+
EatEat
e+
e-
2015-11-27 4
Molecules
Ξ¨+ = π+ 1π π΄ + 1π π΅
Ξ¨β = πβ 1π π΄ β 1π π΅
P. Atkins
Atkins, Fridman Molecular QM
Electrons energy strongly depends on the distance between nuclei.
P. Kowalczyk
πΈ(π ) - usually in numerical form.
Approximations: Morse potentialeg. Lithium
π π = π·π 1 β πβπΌ πβπ0 + π π0
Approximations: Lenard-Jones potential
2015-11-27 5
Electronic states
π π = 4ππ
π
12
βπ
π
6
+ π π0
Electrons energy strongly depends on the distance between nuclei.
πΈ(π ) - usually in numerical form.
Approximations: Morse potentialeg. Lithium
π π = π·π 1 β πβπΌ πβπ0 + π π0
Approximations: Lenard-Jones potential
2015-11-27 6
Electronic states
π π = 4ππ
π
12
βπ
π
6
+ π π0
Wik
iped
ia
Electrons energy strongly depends on the distance between nuclei.
πΈ(π ) - usually in numerical form.
Approximations: Morse potentialeg. Lithium
π π = π·π 1 β πβπΌ πβπ0 + π π0
Approximations: Lenard-Jones potential
2015-11-27 7
Electronic states
π π = 4ππ
π
12
βπ
π
6
+ π π0
Wik
iped
ia
Homonuclear diatomic molecules, eg. H2, Li2, N2, O2
The molecule is diatomic so we are looking for a combination of two orbitals ππ΄ and ππ΅.
overlap integral
2015-11-27 8
Molecules
Ξ¨ = ππ΄ππ΄ + ππ΅ππ΅
π = ΰΆ±ππ΄ππ΅ πΤ¦π > 0πΒ± = ࢱΨ±
β π»0Ψ±πΤ¦π
π+ =πΈππ‘ β π»π΄π΅
1 + π
πβ =πΈππ‘ + π»π΄π΅
1 β π
π»π΄π΄ = ΰΆ±ππ΄β π»0ππ΄πΤ¦π = π»π΅π΅ β πΈππ‘
π»π΄π΅ = ΰΆ±ππ΄β π»0ππ΅πΤ¦π < 0
1s 1s
1su+
1sg+
EatEat
e+
e-
bonding orbital
antibonding orbital
These were
π+ =1
2 1 + ππβ =
1
2 1 β π
ππ΄2 = ππ΅
2 β ππ΄ = Β±ππ΅
2015-11-27 9
Molecules
Ξ¨ = ππ΄ππ΄ + ππ΅ππ΅
π = ΰΆ±ππ΄ππ΅ πΤ¦π > 0
Eat,B
Eat,A
overlap integral
ππ΄2 = ππ΅
2 β ππ΄ = Β±ππ΅
Heteronuclear diatomic molecules, eg. CO, NO, HCl, HF
Heteronuclear diatomic molecules, eg. CO, NO, HCl, HF
2015-11-27 10
Molecules
Ξ¨ = ππ΄ππ΄ + ππ΅ππ΅
π = ΰΆ±ππ΄ππ΅ πΤ¦π > 0π <
Β±Ξ¨β π»0Ψ±πΤ¦π
Β±Ξ¨βΨ±πΤ¦π
π»π΄π΄ β π π»π΄π΅ β πππ»π΄π΅ β ππ π»π΅π΅ β π
ππ΄ππ΅
= 0
ππ΄2 β ππ΅
2
Eat,B
Eat,A
e1
e2
variational method
π ππ΄2 + ππ΅
2 + 2ππ΄ππ΅π = ππ΄2π»π΄π΄ + ππ΅
2π»π΅π΅ + 2ππ΄ππ΅ π»π΄π΅
ππ
πππ΄=
ππ
πππ΅= 0
π»π΄π΄ β πΈππ‘,π΄
π»π΅π΅ β πΈππ‘,π΅
Letβs assume that πΈππ‘,π΄ < πΈππ‘,π΅
The molecule is diatomic so we are looking for a combination of two orbitals ππ΄ and ππ΅.
2015-11-27 11
Molecules
Ξ¨ = ππ΄ππ΄ + ππ΅ππ΅
π = ΰΆ±ππ΄ππ΅ πΤ¦π > 0π <
Β±Ξ¨β π»0Ψ±πΤ¦π
Β±Ξ¨βΨ±πΤ¦π
π»π΄π΄ β π π»π΄π΅ β πππ»π΄π΅ β ππ π»π΅π΅ β π
ππ΄ππ΅
= 0
ππ΄2 β ππ΅
2
Eat,B
Eat,A
e1
e2
variational method
π ππ΄2 + ππ΅
2 + 2ππ΄ππ΅π = ππ΄2π»π΄π΄ + ππ΅
2π»π΅π΅ + 2ππ΄ππ΅ π»π΄π΅
ππ
πππ΄=
ππ
πππ΅= 0
π1 β πΈππ‘,π΄ βπ»π΄π΅ β πΈππ‘,π΄π
2
πΈππ‘,π΅ β πΈππ‘,π΄
π2 β πΈππ‘,π΅ +π»π΄π΅ β πΈππ‘,π΅π
2
πΈππ‘,π΅ β πΈππ‘,π΄
The molecule is diatomic so we are looking for a combination of two orbitals ππ΄ and ππ΅.
Heteronuclear diatomic molecules, eg. CO, NO, HCl, HF
The bonding is strong when:
The large value of the overlap integral π and proportional to it integral π»π΄π΅.The small difference of the energy of atomic orbitals πΈππ‘,π΄, πΈππ‘,π΅.Molecular orbitals do not have to be constructed with atomic orbitals of the same type (π β π or π β π).
2015-11-27 12
Molecules
π»π΄π΄ β π π»π΄π΅ β πππ»π΄π΅ β ππ π»π΅π΅ β π
ππ΄ππ΅
= 0Eat,B
Eat,A
e1
e2
π ππ΄2 + ππ΅
2 + 2ππ΄ππ΅π = ππ΄2π»π΄π΄ + ππ΅
2π»π΅π΅ + 2ππ΄ππ΅ π»π΄π΅
ππ
πππ΄=
ππ
πππ΅= 0
π1 β πΈππ‘,π΄ βπ»π΄π΅ β πΈππ‘,π΄π
2
πΈππ‘,π΅ β πΈππ‘,π΄
π2 β πΈππ‘,π΅ +π»π΄π΅ β πΈππ‘,π΅π
2
πΈππ‘,π΅ β πΈππ‘,π΄
Example: HF molecule
F: (1s)2(2s)2(2p)5 H: (1s)1
1. Similar energy values have 2p of F and 1s of H.2. Only 2pz orbital gives non-zero overlap integral
with 1s (bonding orbital Ο).3. 2 Fluorine electrons 2px i 2 electrons 2py are not
involved in the HF molecular bonding and are called lone pair (wolna para elektronowa)
4. Similarly fluorine 1s and 2s atomic orbitals do not form a bond with the 1s hydrogen electron because of the large energy difference
5. Ground state: 1Ξ£+
2015-11-27 13
Molecules
Eat,B
Eat,Ae1
e2
P. K
ow
alcz
yk
Hybridization and overlap integrals
2015-11-27 14
Molecules
htt
p:/
/sp
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com
/ch
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try/
org
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chem
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2.p
hp
P. K
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Hybridization sp, eg. BeH2
2015-11-27 15
Molecules
The angle between the bonds is 180Λ.
β1 =1
2π β
1
2ππ₯
β2 =1
2π +
1
2ππ₯
Hybridization sp2, eg. C2H4
2015-11-27 16
Molecules
The angle between the bonds is 120Λ.
β1 =1
3π β
1
2ππ₯ β
1
6ππ§
β3 =1
3π +
1
2ππ§
β2 =1
3π +
1
2ππ₯ β
1
6ππ§
P. K
ow
alcz
yk
Ethylene C2H4
Hybridization sp3, eg. CH4
2015-11-27 17
Molecules
The angle between the bonds is 109,5Λ.
β1 =1
2π + ππ₯ + ππ¦ + ππ§
P. K
ow
alcz
yk
Methane CH4
β2 =1
2π + ππ₯ β ππ¦ β ππ§
β3 =1
2π β ππ₯ + ππ¦ β ππ§
β4 =1
2π β ππ₯ β ππ¦ + ππ§
Hybridization sp3, eg. CH4
2015-11-27 18
Molecules
The angle between the bonds is 109,5Λ.
β1 =1
2π + ππ₯ + ππ¦ + ππ§
β2 =1
2π + ππ₯ β ππ¦ β ππ§
β3 =1
2π β ππ₯ + ππ¦ β ππ§
β4 =1
2π β ππ₯ β ππ¦ + ππ§
Methane CH4 Ammonia NH3 Water H2O
http://oen.dydaktyka.agh.edu.pl/dydaktyka/chemia/a_e_chemia/1_3_budowa_materii/01_04_03_2b.htm
Hybridization sp3, eg. CH4
2015-11-27 19
Molecules
The angle between the bonds is 109,5Λ.
β1 =1
2π + ππ₯ + ππ¦ + ππ§
β2 =1
2π + ππ₯ β ππ¦ β ππ§
β3 =1
2π β ππ₯ + ππ¦ β ππ§
β4 =1
2π β ππ₯ β ππ¦ + ππ§
Hybridization
2015-11-27 20
Molecules
htt
p:/
/sp
arkc
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ts.s
par
kno
tes.
com
/ch
emis
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org
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chem
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2.p
hp
htt
p:/
/ww
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cien
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wat
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Hybridization
2015-11-27 21
Molecules
Uranium, a member of the actinide group of elements, can form molecules with five covalent bonds.Each uranium atom has a total of 16 atomic orbitals that are available for bond formation. Gagliardi and Roos used an approach called CASSCF/CASPT2 to model how all the valence orbitals in one atom merge with those in the other atom to form the most stable chemical bond -- that is, the one with minimum energy.
Gagliardi and Roos found that the uranium-uranium bond is more complex than any other known diatomic bond: it contains three normal electron-pair bonds and four weaker one-electron bonds. They also find evidence for ferromagnetic coupling between two electrons, each localized on one of the atoms. This means that all the known forms of covalent bonding are found in the molecule.
Hybridization
2015-11-27 22
Molecules
htt
p:/
/sp
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/ch
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org
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chem
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2.p
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http://oen.dydaktyka.agh.edu.pl/dydaktyka/chemia
Carbon
Benzene molecule
2015-11-27 23
Molecules
Ο-bonds (sp2) are "localized" and form a rigid skeleton, while Ο-electrons forming a bond are delocalized.
Benzene
π = 0,Β±1,Β±2, 3
Six of atomic orbitals 2pz gives an equal contribution to all of the molecular orbitals.
These functions correspond to the waves running around the carbon atoms ring in opposite directions for positive and negative values of π
Ξ¨k =1
6
π=1
6
π2ππ6 ππ ππ§,π
πΈk = πΌ + 2π½ cos2ππ
6π
Benzene molecule
2015-11-27 24
Molecules
π = 0,Β±1,Β±2, 3
Ξ¨k =1
6
π=1
6
π2ππ6 ππ ππ§,π
πΈk = πΌ + 2π½ cos2ππ
6π
Friedrich August Kekule 1829 - 1896
dr hab. Andrzej WysmoΕek
dr inΕΌ. WΕodzimierz StrupiΕski,
dr hab. Andrzej WysmoΕek
dr inΕΌ. WΕodzimierz StrupiΕski,
dr Jacek SzczytkoMichaΕ KluzIzabela Rytarowska
dr Jacek SzczytkoMichaΕ KluzIzabela Rytarowska
dr Jacek SzczytkoMichaΕ KluzIzabela Rytarowska
Orientation is defined by the chiral vector π,π : ππ = π π + π π
Different orientations:
β’ Armchair
β’ Zig-zag
β’ Chiral
J.Basak, D.Mitra, S.Sinha βCarbon nanotube: the next generation sensorsβ presentation PaweΕ Tomasz PΔczkowski
2015-11-27 31
Nanotubes
2015-11-27 32
Nanotubes
Single Wall Nanotube(Zig-Zag Type)
Single Wall Nanotube(Arm-Chair Type)
Uprolling a Graphene(Arm-Chair Type)
Uprolling a Graphene(Zig-Zag Type)
Single Wall Nanotube(Chiral Type)
www.surf.nuqe.nagoya-u.ac.jp/nanotubes/omake/nanotubes/nanotubes.html
f = 0.246 (n2+nm+m2)1/2 / Ο (nm)
Single β twist http://www.ipt.arc.nasa.gov
2015-11-27 33
Nanomachines
Single β bend http://www.ipt.arc.nasa.gov
2015-11-27 34
Nanomachines
Single β compress http://www.ipt.arc.nasa.gov
2015-11-27 35
Nanomachines
Multi β twist http://www.ipt.arc.nasa.gov
2015-11-27 36
Nanomachines
Multi β bend http://www.ipt.arc.nasa.gov
2015-11-27 37
Nanomachines
Multi β compress http://www.ipt.arc.nasa.gov
2015-11-27 38
Nanomachines
Space elevator
2015-11-27 39
Space elevatorhttp://www.spaceelevator.com/
2015-11-27 40
http://www.uc.edu/news/NR.asp?id=5700
Space elevator
2015-11-27 41
Buckminster Fuller pour un exposition en 1967 Γ MontrΓ©al
Fullerenes
2015-11-27 42
Solutions in toluene
Fullerenes
2015-11-27 44
Fullerenes
2015-11-27 46
fcc C60 crystals
Fullerenes
2015-11-27 47
Superconductivity K3C60X.D. Xiang, J.G. Hou, et al. Nature 361, 54, 1993
ZaleΕΌnoΕΔ oporu wΕaΕciwego K3C60 od temperatury ZaleΕΌnoΕΔ Tc od staΕej sieci
PaweΕ Tomasz PΔczkowski
Fullerenes
2015-11-27 48
Too slow Too fast
Accurately
Benzene + C60
http://www.ipt.arc.nasa.gov
2015-11-27 49
Nanomachines
Benzen + CN
Gear Rotation in a Vacuum 200 rot/ns
Powered Sharfhttp://www.ipt.arc.nasa.gov
2015-11-27 50
Nanomachines
Too slow
Accurately
Gear Rotation at RT 50/70/100 rot/ns
Gear Rotation at RT 50 rot/ns
Too fast > 100 rot/ns
http://www.ipt.arc.nasa.gov
2015-11-27 51
Nanomachines
htt
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t.ar
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gov
Gear and Shaft Operation
Powered GearPowered Sharf
Large Gear Drives Small Gear
2015-11-27 52
Nanomachines
Long Gear Rotation at Room Temperature
htt
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t.ar
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gov
Startup Rotating
Rotation of Gears with Two Off-line Rows of Teeth
Zbyt szybko
2015-11-27 53
Nanomachines
βplumberβs nightmareβ
Schwartzite