Hartree-Foc Theory Solving electronic structure problem on computers Hartree product of non-interacting electrons mean field molecular orbitals expectations values one and two electron operators Pauli Principle slater determinant of molecular orbitals expectations values of one and two electron operators energy of slater determinant variation principle optimizing the orbitals in slater determinant one-particle mean-field foc operator self-consistent-field linear combinations atomic orbitals & basissets Roothaan Hall equations
Hartree-Foc Theory for n electrons mean-field approach H = i atomic units 2 2m e 2 i A e 2 Z A 4π 0 r i R A + vmf i (r i ) h i (r i )= 2 i + A independent electrons H = h i (r i ) i Z A r ia + v mf i (r i ) one-electron wavefunctions (molecular orbitals) h i (r) i (r) = i i (r) orthonormal i (r) j (r)dr = δ ij Hartree product of n distinghuisable electrons Ψ(r 1, r 2,...,r n )= 1 (r 1 ) 2 (r 2 )... n (r n )
Hartree-Foc Theory for n electrons indistinguishable electrons fermions with 3 spatial and 1 spin coordinate (4D) {x} = {r,s} Pauli principle Ψ(r 1, x 2,..,x i, x j,...,x n )= Ψ(x 1, x 2,..,x j, x i,...,x n ) spin orbitals ϕ i (x) = i (r)α(s) i (r)β(s) spin functions α(s)β(s)ds = δ αβ
Hartree-Foc Theory for n electrons anitsymmetric linear combination of Hartree products: i.e. 2 electrons Ψ(x 1, x 2 )= 1 2 [ϕ 1 (x 1 )ϕ 2 (x 2 ) ϕ 2 (x 1 )ϕ 1 (x 2 )] n electrons: Slater determinant Ψ(x 1, x 2,..,x n )= 1 n ϕ 1 (x 1 ) ϕ 1 (x 2 ).. ϕ 1 (x n ) ϕ 2 (x 1 ) ϕ 2 (x 2 ).. ϕ 2 (x n ) ϕ n (x 1 ) ϕ n (x 2 ).. ϕ n (x n )
Hartree-Foc Theory for n electrons anitsymmetric linear combination of Hartree products: i.e. 2 electrons Ψ(x 1, x 2 )= 1 2 [ϕ 1 (x 1 )ϕ 2 (x 2 ) ϕ 2 (x 1 )ϕ 1 (x 2 )] n electrons: Slater determinant Ψ(x 1, x 2,..,x n )= 1 n ϕ 1 (x 1 ) ϕ 1 (x 2 ).. ϕ 1 (x n ) ϕ 2 (x 1 ) ϕ 2 (x 2 ).. ϕ 2 (x n ) ϕ n (x 1 ) ϕ n (x 2 ).. ϕ n (x n )
Hartree-Foc Theory for n electrons Expectations values for one and two electron operators Hartree product (no spin) Ô1 = a a (x 1 )ô(r 1 ) a (r 1 )dr 1 Ô2 = 1 2 a b a (r 1 ) b (r 2)ô(r 1, r 2 ) a (r 1 ) b (r 2 )dr 1 dr 2 Slater determinant (spin, Pauli principle) Ô1 = a a (x 1 )ô(r 1 ) a (x 1 )dx 1 Ô2 = 1 2 1 2 a a b a (x 1 ) b (x 2)ô(r 1, r 2 ) a (x 1 ) b (x 2 )dx 1 dx 2 b a (x 1 ) b (x 2)ô(r 1, r 2 ) b (x 1 ) a (x 2 )dx 1 dx 2 Ô2 = 1 2 a b a (x 1 ) b (x 2)ô(r 1, r 2 )(1 ˆp 12 ) a (x 1 ) b (x 2 )dx 1 dx 2
Wassermoleül 2 H + 1 O 8+ 10 Eletronen 10 Moleülorbitale
Wassermoleül 2 H+ 1 O8+ 10 Eletronen 10 Moleülorbitale
2 H+ 1 O8+ 10 Eletronen 10 Moleülorbitale Energie Wassermoleül
Hartree-Foc theory mean field approach vary orbitals until until self-consistency (SCF)
Hartree-Foc Theory for n electrons Hartree-Foc eigenvalue equations ˆf(x 1 )ϕ i (r 1 )= i ϕ(r 1 ) solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals step 2: expand spatial orbitals in basis functions restricted Hartree Foc electron pair with opposite spin in same spatial orbital ϕ i (x) = j (r)α(s) ϕ i+1 (x) = j (r)β(s)
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals ˆf(x 1 ) i (r 1 )α(s 1 ) = ĥ0 (r 1 ) i (r 1 )α(s 1 ) + n/2 + n/2 n/2 n/2 (r 2 )α (s 2 ) 1 (r 2 )α(s 2 ) i (r 1 )α(s 1 )dr 2 ds 2 (r 2 )β (s 2 ) 1 (r 2 )β(s 2 ) i (r 1 )α(s 1 )dr 2 ds 2 (r 2 )α (s 2 ) 1 i (r 2 )α(s 2 ) (r 1 )α(s 1 )dr 2 ds 2 (r 2 )β (s 2 ) 1 i (r 2 )α(s 2 ) (r 1 )β(s 1 )dr 2 ds 2
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals ˆf(x 1 ) i (r 1 )α(s 1 ) = ĥ0 (r 1 ) i (r 1 )α(s 1 ) + n/2 + n/2 n/2 n/2 (r 2 )α (s 2 ) 1 (r 2 )α(s 2 ) i (r 1 )α(s 1 )dr 2 ds 2 (r 2 )β (s 2 ) 1 (r 2 )β(s 2 ) i (r 1 )α(s 1 )dr 2 ds 2 (r 2 )α (s 2 ) 1 i (r 2 )α(s 2 ) (r 1 )α(s 1 )dr 2 ds 2 (r 2 )β (s 2 ) 1 i (r 2 )α(s 2 ) (r 1 )β(s 1 )dr 2 ds 2
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals ˆf(x 1 ) i (r 1 )α(s 1 ) = ĥ0 (r 1 ) i (r 1 )α(s 1 ) + n/2 + n/2 n/2 (r 2 ) 1 (r 2 ) i (r 1 )α(s 1 )dr 2 (r 2 ) 1 (r 2 ) i (r 1 )α(s 1 )dr 2 (r 2 ) 1 i (r 2 ) (r 1 )α(s 1 )dr 2
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals α (s 1 ) ˆf(x 1 )α(s 1 )ds 1 i (r 1 ) = α (s 1 )ĥ0 (r 1 )(r 1 )α(s 1 )ds 1 + n/2 + n/2 n/2 α (s 1 ) (r 2) 1 (r 2 ) i (r 1 )α(s 1 )dr 2 ds 1 α (s 1 ) (r 2) 1 (r 2 ) i (r 1 )α(s 1 )dr 2 ds 1 α (s 1 ) (r 2) 1 i (r 2 ) (r 1 )α(s 1 )dr 2 ds 1 Hartree-Foc eigenvalue equation for spatial orbitals ˆf(r 1 ) i (r 1 ) = ĥ0 (r 1 )(r 1 ) +2 n/2 (r 2 ) 1 (r 2 ) i (r 1 )dr 2 n/2 (r 2 ) 1 i (r 2 ) (r 1 )dr = i i (r 1 )
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 1: get rid of spin and express in real spatial orbitals ˆf(r 1 ) i (r 1 ) = ĥ0 (r 1 )(r 1 ) +2 n/2 (r 2 ) 1 (r 2 ) i (r 1 )dr 2 n/2 (r 2 ) 1 i (r 2 ) (r 1 )dr = i i (r 1 ) step 2: expand spatial orbitals in basis functions (basisset) i (r) = j c ij γ j (r R j )
Hartree-Foc Theory for n electrons linear combination of atomic orbitals i (r) = j c ij γ j (r R j ) hydrogen-lie orbitals (one possibility out of many...) γ 1 = ψ 1s (ζ 1 ) γ 2 = ψ 2s (ζ 2 ) γ 3 = ψ 2p (ζ 3 ) γ 4 =...
Wasserstoffmoleül Lineare Kombination von einzelne Wasserstoff-Orbitale - = 2(1 + S12 ) atomorbital moleülorbital + = 2(1 + S12 )
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 2: expand spatial orbitals in basis functions ˆf(r 1 ) i (r 1 )= i i (r 1 ) i (r) = j c ij γ j (r R j ) ν ˆf(r 1 ) ν c νi γ ν (r 1 )= i c νi γ ν (r 1 ) c νi γµ(r 1 ) ˆf(r 1 )γ ν (r 1 )dr 1 = i c νi ν ν γ µ (r 1 )γ ν (r 1 )dr 1
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically step 2: expand spatial orbitals in basis functions (basisset) c νi γµ(r 1 ) ˆf(r 1 )γ ν (r 1 )dr 1 = i c νi ν ν γ µ (r 1 )γ ν (r 1 )dr 1 express in terms of matrices F µν c νi = i ν ν S µν c νi solution if, and only if FC = SC F i S =0
Hartree-Foc Theory for n electrons solving non-linear eigenvalues equations numerically non-linear: F depends on C F µν = γ µ(r 1 )ĥ0 (r 1 )γ ν (r 1 )dr 1 +2 a γ µ (r 1 ) a(r 2 ) 1 a (r 2 )γ ν (r 1 )dr 1 dr a γ µ (r 1 ) a(r 2 ) 1 γ ν (r 2 ) a (r 1 )dr 1 dr F µν = h 0 µν +2 a a κ κ λ c κac λa λ c κac λa γ µ (r 1 )γ κ(r 2 ) 1 γ λ (r 2 )γ ν (r 1 )dr 1 dr γ µ (r 1 )γ κ(r 2 ) 1 γ ν (r 2 )γ a (r 1 )dr 1 dr
Hartree-Foc Roothaan-Hall equations non-linear eigenvalue problem Fc = i Sc practical algorithm iterate until self-consistency pre-compute integrals of basisset F µν = γ µ ˆf γ ν S µν = γ µ γ ν
Basissets minimal basis (1 function per shell) H-He: 1s (1) Li-Ne: 1s, 2s, 2px, 2py, 2pz (5) Na-Ar: 1s, 2s, 2px, 2py, 2pz, 3s, 3px, 3py, 3pz (9) Slater-type orbitals computationally demanding f 1s (ζ, r) =exp[ ζr] Gaussian-type orbitals computationally convenient g 1s (α, r) = (8α 3 /π 3 ) 1/4 exp[ αr 2 ] g (α, r) 2px = (128α 5 /π 3 ) 1/4 x exp[ αr 2 ] g (α, r) 3dxy = (2048α 7 /π 3 ) 1/4 xy exp[ αr 2 ]
Basissets Gaussian-type orbitals computationally convenient, but not as accurate as Slater-type orbitals linear combination (contraction) of several gaussians (primitives) STO-3G CGF 1s = 3 i d i,1sg 1s (α i,1s ) CGF 2s = 3 i d i,2sg 1s (α i,2sp ) CGF 2p = 3 i d i,2pg 2p (α i,2sp ) least-square fit to Slater orbitals min SF 1s (r) CGF 1s (r))dr] 2 min SF 2s (r) CGF 2s (r) dr SF 2p (r) CGF 2p (r) dr 2
Basissets Double-Zeta basis two basisfunctions (contractions) per valence orbital 3-21G, 4-31G, 6-31G H-He: 1s = 2 i d i,1sg 1s (α i,1s ) 1s = g 1s (α i,1s ) Li-Ne: 1s = 3 i d i,1sg 1s (α i,1s ) 2s = 2 i d i,2s g 1s(α i,2sp ) 2s = g 1s (α i,2sp ) 2p = 2 i d i,2p g 2p(α i,2sp ) 2p = g 2p (α i,2sp )
Basissets Double-Zeta basis with polarization functions two basisfunctions (contractions) per valence orbital Li-Ne: 3d functions (*) H-He: 2p functions (**) 3-21G*, 4-31G*, 6-31G*, 6-31G**