The Construction and Interpretation of McSCF Wavefunctions

Schmidt, Michael W.; Gordon, Mark S.

doi:10.1146/annurev.physchem.49.1.233

Cited by 658 publications

(588 citation statements)

References 205 publications

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“…56 This CASVB method bears close relationship to the localization procedure of CASSCF that leads to VB-like information. 57,58 The Generalized Resonating Valence Bond Method Multiconfigurational extensions of the GVB method have been specifically devised for delocalized electronic systems, like benzene, whose qualitative description requires the use of two, or more, resonance structures, and for which the one-configuration VB approximation is not appropriate. This situation is widespread, including a wide variety of open-shell electronic states, as for example allyl radical and its analogs, pentadienyl anion and its analogs, transition states of chemical reactions, core-ionized diatoms, n-* excited molecules containing two equivalent carbonyl groups, n-ionized molecules having equivalent remote lone pairs, etc.…”

Section: The Spin-coupled Valence Bond Methodsmentioning

confidence: 99%

A survey of recent developments in ab initio valence bond theory

Hiberty

Shaik

2006

J Comput Chem

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Starting from the 1980s and onwards, Valence Bond theory has been enjoying renaissance that is characterized by the development of a growing number of ab initio methods, and by many applications to chemical reactivity and to the central paradigms of chemistry. Owing the increase of computational power of modern computers and to significant advances in the methodology, valence bond theory begins to offer a sound and attractive alternative to Molecular Orbital theory. This review aims at summarizing the most important developments of ab initio valence bond methods during the last two or three decades, and is primarily devoted to a description of what the various methods can actually achieve within their specific scopes and limitations. Key available softwares are surveyed.

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Section: The Spin-coupled Valence Bond Methodsmentioning

confidence: 99%

A survey of recent developments in ab initio valence bond theory

Hiberty

Shaik

2006

J Comput Chem

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“…10a-d Closed-shell CCSD(T) calculations were carried out with the coupled cluster code recently introduced into GAMESS. 11 Since both reactions involve O 2 , which is intrinsically multiconfigurational, the potential energy surfaces were initially studied using multiconfigurational self-consistent field (MCSCF) wave functions, 12 with a full valence active space within the fully optimized reaction space 13,14 (FORS) model, for both the singlet and triplet surfaces. The full valence MCSCF active space consists of 16 electrons in 12 orbitals, denoted MCSCF(16,12).…”

Section: Computational Detailsmentioning

confidence: 99%

Potential Energy Surfaces for the Reactions Si + O₂

Adamovic

Gordon

2004

J. Phys. Chem. A

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This study investigates the reaction between silicon atom in its ground electronic state and ground-state molecular oxygen. The potential energy surfaces for the two competing reactions Si(3P) + O2(3Σg-) = SiO2(1Σg+) vs Si(3P) + O2(3Σg-) = SiO(1Σg+) + O(3P) are analyzed and compared. The lowest energy potential energy surface (PES) for each multiplicity is investigated within Cs symmetry. The entire potential energy surfaces were described using the multi-configuration self-consistent field (MCSCF) level of theory, augmented by multireference second order perturbation theory (MRMP2). Singles and doubles coupled cluster theory with perturbative triples, CCSD(T), energy calculations were also done at the MCSCF geometries. It is shown that the singlet reaction is thermodynamically favored, that the singlet product, SiO2 (1Σ g+), is the global minimum, and that both reactions have no net barrier. Extrapolation of the CCSD(T)/cc-pVTZ reaction enthalpies to the complete basis set (CBS) limit brings the calculations into excellent agreement with experimental data. Disciplines Chemistry CommentsReprinted (adapted) May 18, 2004; In Final Form: July 2, 2004 This study investigates the reaction between silicon atom in its ground electronic state and ground-state molecular oxygen. The potential energy surfaces for the two competing reactions Si( 3 P)+ O( 3 P) are analyzed and compared. The lowest energy potential energy surface (PES) for each multiplicity is investigated within C s symmetry. The entire potential energy surfaces were described using the multi-configuration self-consistent field (MCSCF) level of theory, augmented by multireference second order perturbation theory (MRMP2). Singles and doubles coupled cluster theory with perturbative triples, CCSD(T), energy calculations were also done at the MCSCF geometries. It is shown that the singlet reaction is thermodynamically favored, that the singlet product, SiO 2 ( 1 Σ g + ), is the global minimum, and that both reactions have no net barrier. Extrapolation of the CCSD(T)/cc-pVTZ reaction enthalpies to the complete basis set (CBS) limit brings the calculations into excellent agreement with experimental data.

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“…Parts of the ground and the lowest excited-state potential energy surfaces corresponding to hydrogen transfer reactions were studied using multiconfigurational MCSCF wave functions 8 and Dunning-Hay double-+ polarization (DZP) basis sets. 9 The MCSCF active spaces include all π electrons and π orbitals: four π bonds, four corresponding antibonding orbitals, and one nitrogen π lone pair.…”

Section: Theoretical Approachmentioning

confidence: 99%

The Ground and Excited State Hydrogen Transfer Potential Energy Surface in 7-Azaindole

Chaban

Gordon

1998

J. Phys. Chem. A

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Multireference wave functions, augmented by second-order perturbation theory, are used to examine the hydrogen transfer process in the ground and first excited states of 7-azaindole and in the 1:1 7-azaindole:water complex. The presence of one water molecule dramatically reduces the barrier to proton transfer in both electronic states. In the excited state the order of the two tautomers is reversed, and the barrier for the hydrogen transfer from the (now higher energy) normal structure to the tautomer in the presence of one water is estimated to be ≤6 kcal/mol. Disciplines Chemistry CommentsReprinted (adapted) ReceiVed: September 18, 1998; In Final Form: NoVember 4, 1998 Multireference wave functions, augmented by second-order perturbation theory, are used to examine the hydrogen transfer process in the ground and first excited states of 7-azaindole and in the 1:1 7-azaindole: water complex. The presence of one water molecule dramatically reduces the barrier to proton transfer in both electronic states. In the excited state the order of the two tautomers is reversed, and the barrier for the hydrogen transfer from the (now higher energy) normal structure to the tautomer in the presence of one water is estimated to be e6 kcal/mol.

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The Construction and Interpretation of McSCF Wavefunctions

Cited by 658 publications

References 205 publications

A survey of recent developments in ab initio valence bond theory

A survey of recent developments in ab initio valence bond theory

Potential Energy Surfaces for the Reactions Si + O₂

The Ground and Excited State Hydrogen Transfer Potential Energy Surface in 7-Azaindole

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The Construction and Interpretation of McSCF Wavefunctions

Cited by 658 publications

References 205 publications

A survey of recent developments in ab initio valence bond theory

A survey of recent developments in ab initio valence bond theory

Potential Energy Surfaces for the Reactions Si + O2

The Ground and Excited State Hydrogen Transfer Potential Energy Surface in 7-Azaindole

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Product

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Potential Energy Surfaces for the Reactions Si + O₂