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Anion Electronic Structure and Correlated, One-electron Theory. J. V. Ortiz Department of Chemistry and Biochemistry Auburn University www.auburn.edu/cosam/JVOrtiz Workshop on Molecular Anions and Electron-Molecule Interactions in Honor of Professor Kenneth Jordan July 1, 2007

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Anion electronic structure and correlated one electron theory

Anion Electronic Structure and Correlated, One-electron Theory

J. V. Ortiz

Department of Chemistry and Biochemistry

Auburn University

www.auburn.edu/cosam/JVOrtiz

Workshop on Molecular Anions and Electron-Molecule Interactions in Honor of

Professor Kenneth Jordan

July 1, 2007

Park City, Utah


Acknowledgments

Funding Theory

National Science Foundation

Defense Threat Reduction Agency

Acknowledgments

  • Symposium Organizers

  • Jack Simons

  • Brad Hoffman

  • Auburn University

  • Department of Chemistry and Biochemistry

  • Auburn Coworkers

  • UNAM Collaborators:

  • Ana Martínez

  • Alfredo Guevara


Quantum chemistry s missions

Deductive agenda: Theory

Deduce properties of molecules from quantum mechanics

Calculate chemical data, especially if experiments are difficult or expensive

Inductive agenda:

Identify and explain patterns in structure, spectra, energetics, reactivity

Deepen and generalize the principles of chemical bonding

Quantum Chemistry’s Missions

G. N. Lewis

E. Schrödinger


Electron Propagator Theory

Theory

Exactness

Interpretation

Molecular Orbital

Theory

Applications


One electron equations

Hartree Fock Theory Theory

Hartree Fock Equations:

(Tkin + Unucl + JCoul - Kexch)φiHF ≡

F φiHF=εiHF φiHF

Same potential for all i:

core, valence, occupied, virtual.

εiHF includes Coulomb and exchange contributions to IEs and EAs

Electron Propagator Theory

Dyson Equation:

[F + ∑(εiDyson)]φiDyson = εiDyson φiDyson

Self energy, ∑(E): Energy dependent, nonlocal potential that varies for each electron binding energy

εiDyson includes Coulomb, exchange, relaxation and correlation contributions to IEs and EAs

φiDyson describes effect of electron detachment or attachment on electronic structure

One-electron Equations


Dyson orbitals feynman dyson amplitudes
Dyson Orbitals Theory(Feynman-Dyson Amplitudes)

  • Electron Detachment (IEs)

    φiDyson(x1) =

    N-½∫ΨN(x1,x2,x3,…,xN)Ψ*i,N-1(x2,x3,x4,...,xN)

    dx2dx3dx4…dxN

  • Electron Attachment (EAs)

    φiDyson(x1) =

    (N+1)-½∫ Ψi,N+1(x1,x2,x3,...,xN+1)Ψ*N(x2,x3,x4,…,xN+1) dx2dx3dx4…dxN+1

  • Pole strength

    Pi = ∫|φiDyson(x)|2dx

    0 ≤ Pi ≤ 1


Electron propagator concepts
Electron Propagator Concepts Theory

Electron Correlation

Dyson Orbital

Canonical MO

Correlated Electron

Binding Energy

Orbital Energy

Integer Occupation

Numbers

Pole Strengths

Independent-Particle

Potential

Energy-dependent,

Self-Energy


Accuracy versus interpretability
Accuracy Theoryversus Interpretability

  • Does electron propagator theory offer a solution to Mulliken’s dilemma?

The more accurate the

calculations become,

the more the concepts

vanish into thin air.

- R. S. Mulliken



Dyson orbitals for u and t ies
Dyson Orbitals for U and T IEs Theory

Uracil

π1

σ-

π2

σ+

π3

Thymine

Methyl (CH3) participation


Uracil versus thymine
Uracil Theoryversus Thymine

  • Methyl group destabilizes π orbitals with large amplitudes at nearest ring atom

  • Therefore, IE(T) < IE(U)

  • Valid principles for substituted DNA bases, porphyrins and other organic molecules


A self energy for large molecules p3
A Self-Energy for TheoryLarge Molecules: P3

  • Neglect off-diagonal elements of Σ(E) in canonical MO basis: φiDyson(x) = Pi½φiHF-CMO(x)

  • Partial summation of third-order diagrams

  • Arithmetic bottleneck: oN4 (MP2 partial integral transformation)

  • Storage bottleneck: o2v2 in semidirect mode

  • Abelian, symmetry-adapted algorithm in G03


Formulae for p3 e
Formulae for TheoryΣP3(E)

ΣP3pq(E) =

½Σiab <pi||ab><ab||qi> Δ(E)-1iab +

½Σaij <pa||ij>(<ij||qa> + Wijqa) Δ(E)-1aij +

½Σaij Upaij(E)<ij||qa>Δ(E)-1aij

where

Δ(E)-1pqr = (E + εp – εq – εr)-1

Wijqa = ½Σbc<bc||qa><ij||bc> Δ-1ijbc

+ (1-Pij)Σbk<bi||qk><jk||ba> Δ-1jkab

Upaij(E) = - ½Σkl<pa||kl><kl||ij> Δ(E)-1akl

- (1 – Pij) Σbk<pb||jk><ak||bi> Δ(E)-1bjk


P3 performance
P3 Performance Theory

  • 31 Valence IEs of Closed-Shell Molecules:

    (N2,CO,F2,HF,H2O,NH3,C2H2,C2H4,CH4,HCN,H2CO)

    MAD (eV) = 0.20 (tz)

  • 10 VEDEs of Closed-Shell Anions:

    (F-,Cl-,OH-,SH-,NH2-,PH2-,CN-,BO-,AlO-,AlS-)

    MAD (eV) = 0.25 (a-tz)

  • Arithmetic bottleneck: o2v3 for Wijqa

  • Storage bottleneck: <ia||bc> for Wijqa


Recent applications porphyrins and fullerenes
Recent Applications: TheoryPorphyrins and Fullerenes


Invitation to propagate
Invitation to Propagate Theory

Input to Gaussian 03

# OVGF 6-311G** iop(9/11=10000)

P3 Electron Propagator for Water

0 1

O

H 1 0.98

H 1 0.98 2 105.

Available diagonal approximations for Σ(E):

Second order, Third order, P3, OVGF (versions A, B & C)


Nucleotides gaseous spectra
Nucleotides: Gaseous Spectra Theory

  • Nucleotides: phosphate-sugar-base DNA fragments

  • Electrospray ion sources

  • Magnetic bottle detection

  • High resolution laser spectroscopy of ions, mass spectrometry

  • Goal: predict photoelectron spectra of anionic nucleotides (vertical electron detachment energies or VEDEs)


Photoelectron spectra of 2 deoxybase 5 monophosphate anions
Photoelectron Spectra of Theory2’-deoxybase 5’-monophosphate Anions

DAMP

Anomalous peak for dGMP

Base = adenine

DCMP

G: lowest IE

of DNA bases

Base = cytosine

DGMP

Base = guanine

Dyson orbitals for

lowest VEDEs:

phosphate or base?

DTMP

Base = thymine

L-S.Wang, 2004


Damp isomers and energies
DAMP Isomers and Energies Theory

0 kcal/mol

4.62

4.66


Damp vedes ev and dyson orbitals
DAMP VEDEs (eV) Theoryand Dyson Orbitals


Dgmp isomers and energies
DGMP Isomers and Energies Theory

0 kcal/mol

5.1

9.2


Dgmp vedes ev and dyson orbitals
DGMP VEDEs (eV) Theoryand Dyson Orbitals


Hydrogen bonds dgmp vs damp
Hydrogen Bonds: DGMP vs DAMP Theory

  • DGMP: G amino to Phosphate oxygen

  • DAMP: Sugar hydroxy to Phosphate oxygen


Nucleotide electronic structure
Nucleotide Electronic Structure Theory

  • Phosphate anion reduces Base VEDEs by several eV

  • Base also increases Phosphate VEDEs

  • Therefore, Base and Phosphate VEDEs

    are close

  • Differential correlation effects are large

  • Koopmans ordering is not reliable


A simple renormalized self energy p3
A Simple, Renormalized Self-Energy: P3+ Theory

ΣP3+pq(E) =

½Σiab <pi||ab><ab||qi> Δ(E)-1iab +

[1+Y(E)]-1 ½Σaij<pa||ij>(<ij||qa> + Wijqa) Δ(E)-1aij + ½Σaij Upaij(E)<ij||qa>Δ(E)-1aij

where

Y(E) = {-½Σaij<pa||ij>Wijqa Δ(E)-1aij} {½Σaij<pa||ij><ij||qa> Δ(E)-1aij}-1


P3 performance1
P3+ Performance Theory

  • 31 Valence IEs of Closed-Shell Molecules:

    (N2,CO,F2,HF,H2O,NH3,C2H2,C2H4,CH4,HCN,H2CO)

    MAD (eV) = 0.19 (tz), 0.19 (qz)

  • 10 VEDEs of Closed-Shell Anions:

    (F-,Cl-,OH-,SH-,NH2-,PH2-,CN-,BO-,AlO-,AlS-)

    MAD (eV) = 0.11 (a-tz), 0.13 (a-qz)


Reactivity of al 3 o 3 with h 2 o
Reactivity of Al Theory3O3- with H2O

  • Wang: first anion photoisomerization

  • Jarrold: Al3O3-(H2O)n photoelectron spectra n=0,1,2

  • Distinct profile for n=1

  • Similar spectra for n=2 and n=0


Al 3 o 3 photoelectron spectrum
Al Theory3O3- Photoelectron Spectrum

Book

Kite


Cluster vedes and dyson orbitals
Cluster VEDEs and Dyson Orbitals Theory

Al3O3-

Al3O4H2-

Al3O5H4-


Strong initial state correlation
Strong Initial State Correlation Theory

  • Need better reference orbitals for:

    diradicaloids, bond dissociation, unusual bonding …

  • Generate renormalized self-energy with approximate Brueckner reference determinant


A versatile self energy bd t1
A Versatile Self-Energy: BD-T1 Theory

  • Asymmetric Metric:

    (X|Y)=

    <Brueckner|[X†,Y]+(1+T2)|Brueckner>

  • Galitskii-Migdal energy =

    BD (Brueckner Doubles, Coupled-Cluster)

  • Operator manifold: f~a†aa=f3

  • Discard only 2ph-2hp couplings


Applications of the bd t1 approximation
Applications of the TheoryBD-T1 Approximation

  • Vertical Electron Detachment Energies of Anions: MAD=0.03 eV

  • 1s Core Ionization Energies: MAD = 0.2%

  • Valence IEs of Closed-Shell Molecules:

    MAD = 0.15 eV

  • IEs of Biradicaloids: MAD = 0.08 eV


Bowen s photoelectron spectrum of nh 4
Bowen’s Photoelectron Spectrum of NH Theory4-

B: Mysterious low-VEDE peak

Not due to hot NH4-

Variable relative intensity

Another isomer of NH4-?

A: H- detachment

with vibrational

excitation of NH3

X: H-(NH3)

NH3 increases H- VEDE

X

B

x300

A


Computational search nh 4 structures
Computational Search: TheoryNH4- Structures

Hydride anion: H-

H-(NH3) constituents:

Ammonia molecule: NH3

Lewis: 1 electron pair

H nucleus has 1+ charge

Negative charge attracts

+ end of polar NH bond

Lewis: 3 electron pairs

shared in polar NH bonds

+ 1 unshared pair on N

Partial + charge on H’s

Partial – charge on N

Anion(molecule)

structure

accounts for

dominant peaks


Computational search what is the structure for the low vede peak
Computational Search: TheoryWhat is the structure for the low-VEDE peak?

Idea: NH2-(H2) anion-molecule complex

Reject: spectral peak would be high-VEDE, not low

Idea: NH4- has 5 valence e- pairs

Deploy in 4 N-H bonds and 1 unshared pair

at the 5 vertices of a trigonal biprism or

square pyramid

Calculations find no such structures!

Instead, they spontaneously rearrange ….


To a heretical structure
….to a heretical structure! Theory

Tetrahedral NH4- has 4

equivalent N-H bonds

Defies Lewis theory

Defies valence shell

electron pair

repulsion theory

Structure similar to that of NH4+

So where are the 2 extra electrons?


Structural confirmation experiment and theory
Structural Confirmation: TheoryExperiment and Theory

Predicted VEDEs from Electron Propagator Theory

for Anion(molecule) and Tetrahedral forms of NH4-

coincide with peaks from photoelectron spectrum


Dyson orbitals for vedes of nh 4
Dyson Orbitals for VEDEs of NH Theory4-

H-(NH3) has 2 electrons

in hydride-centered orbital

with minor N-H delocalization.

VEDE is 1.07 eV

Tetrahedral NH4- has 2

diffuse electrons located

chiefly outside of NH4+ core.

VEDE is 0.47 eV


Irc t d nh 4 h nh 3
IRC: T Theoryd NH4- -> H-(NH3)

Energy (au)

Intrinsic Reaction Coordinate


Double rydberg anions
Double Rydberg Anions Theory

  • Highly correlated motion of two diffuse (Rydberg) electrons in the field of a positive ion (NH4+ , OH3+)

  • United atom limit is an alkali anion: Na-

  • Extravalence atomic contributions in Dyson orbitals

NH4-

OH3-


Irc c 3v oh 3 h h 2 o

E Theoryact = 5.1

Erx = -39.9

IRC: C3v OH3- -> H-(H2O)


Bowen s photoelectron spectrum of n 2 h 7
Bowen’s Photoelectron Spectrum of N Theory2H7-

X: H-(NH3)2 e- detachment

B & C: two low EBEs!

C

B

X

x500

A


Calculated n 2 h 7 structures
Calculated N Theory2H7- Structures

  • H-(NH3)2 anion-

    molecule complex

  • NH4-(NH3) anion-

    molecule complex

    with tetrahedral NH4-

  • N2H7- with hydrogen bond (similar to N2H7+ )


N 2 h 7 vedes and dyson orbitals
N Theory2H7- VEDEs and Dyson Orbitals

H-(NH3)2 has hydride centered Dyson orbital

EPT predicts 1.49 eV for VEDE

Peak observed in spectrum at 1.46 ± 0.02 eV

Dyson orbital concentrated near NH4-

EPT predicts 0.60 eV for VEDE

Peak observed at 0.58 ± 0.02 eV

Dyson orbital concentrated near 3 hydrogens

EPT predicts 0.42 eV for VEDE

Peak observed at 0.42 ± 0.02 eV


Assignment of n 3 h 10 ebes to double rydberg anions
Assignment of N Theory3H10-EBEs to Double Rydberg Anions

  • (NH4-)(NH3)2 : 0.66 (Expt.) 0.68 (EPT)

  • (N2H7-)(NH3) : 0.49 (Expt.) 0.49 (EPT)

  • (N3H10-) : 0.42 (Expt.) 0.40 (EPT)

x800


O 2 h 5 and n 2 h 7 structures
O Theory2H5- and N2H7- Structures

Molecule-Hydride

Bridge

Ion-dipole


O 2 h 5 vedes and dyson orbitals
O Theory2H5- VEDEs and Dyson Orbitals

H-(H2O)2 VEDE: 2.36 eV

H-bridged VEDE: 0.48 eV

Ion-dipole VEDE: 0.74 eV


Electron pair concepts old and new
Electron Pair Concepts: Old and New Theory

Chemical bonds arise

from pairs of electrons

shared betweenatoms

G.N. Lewis

I. Langmuir

W.N. Lipscomb

Unshared pairs

localized on single atoms

affect bond angles

Molecular cations may

bind an e- pair peripheral

to nuclear framework:

Double Rydberg Anions

R.J. Gillespie

R.S. Nyholm


Electron propagator theory and quantum chemistry s missions
Electron Propagator Theory and Quantum Chemistry Theory’s Missions

  • Deductive, quantitative theory:

    Prediction and interpretation enable dialogue with experimentalists requiring accurate data

  • Inductive, qualitative theory:

    Orbital formalism generalizes and deepens qualitative notions of electronic structure, relating structure, spectra and reactivity


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