Theory of the Electronic Energy Levels of Simple Hydrides

Stehn, J. R.

doi:10.1063/1.1750005

Cited by 20 publications

(7 citation statements)

References 23 publications

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“…The energies of the singlet and triplet states of a diatomic molecule can be readily expressed in terms of Coulomb and exchange integrals via Slater's rules (or alternatively, Dirac vector rules). − Valence-bond expressions, where the Coulomb and exchange integrals are between atomic orbitals, have been reported for diatomic hydrides, , subject to the following assumptions:…”

Section: Formulation Of the Methodsmentioning

confidence: 99%

“…This completes the construction of the V-diabatic potential energy curves for the HBr molecule or for a halogen bond in a polyatomic molecule, if only singlet and triplet states are considered. Similar expressions to those in eqs 3−9 can be derived for electronic states of other spin multiplicity …”

Section: Formulation Of the Methodsmentioning

confidence: 99%

“…Similar expressions to those in eqs 3−9 can be derived for electronic states of other spin multiplicity. 97 The construction of a consistent F-diabatic representation for a single-channel process such as HBr → H( 2 S) + Br( 2 P) is, in principle, straightforward, and will be discussed next. Note that the discussion is general in that it does not involve the assumptions of eqs 5a and 5b.…”

Section: -64mentioning

confidence: 99%

“…We will assume from the outset that the ab initio valence adiabatic singlet wave functions [95][96][97] Valence-bond expressions, where the Coulomb and exchange integrals are between atomic orbitals, have been reported for diatomic hydrides, 97,98 subject to the following assumptions: With these assumptions, the two doublet electronic states of the H and Br atoms generate two singlet and two triplet V-adiabatic states for the HBr molecule, and these can be written as 97,98 , 2 4 ) ( …”

Section: -64mentioning

confidence: 99%

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A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Valero

Truhlar

2007

J. Phys. Chem. A

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A diabatic representation is convenient in the study of electronically nonadiabatic chemical reactions because the diabatic energies and couplings are smooth functions of the nuclear coordinates and the couplings are scalar quantities. A method called the fourfold way was devised in our group to generate diabatic representations for spin-free electronic states. One drawback of diabatic states computed from the spin-free Hamiltonian, called a valence diabatic representation, for systems in which spin-orbit coupling cannot be ignored is that the couplings between the states are not zero in asymptotic regions, leading to difficulties in the calculation of reaction probabilities and other properties by semiclassical dynamics methods. Here we report an extension of the fourfold way to construct diabatic representations suitable for spincoupled systems. In this article we formulate the method for the case of even-electron systems that yield pairs of fragments with doublet spin multiplicity. For this type of system, we introduce the further simplification of calculating the triplet diabatic energies in terms of the singlet diabatic energies via Slater's rules and assuming constant ratios of Coulomb to exchange integrals. Furthermore, the valence diabatic couplings in the triplet manifold are taken equal to the singlet ones. An important feature of the method is the introduction of scaling functions, as they allow one to deal with multibond reactions without having to include Comparison of the spin-coupled adiabatic energies obtained from the spin-valence diabatics with those obtained by ab initio calculations with geometry-dependent spin-orbit matrix elements shows that the new method is sufficiently accurate for practical purposes. The method formulated here should be most useful for systems with a large number of atoms, especially heavy atoms, and/or a large number of spin-coupled electronic states.

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Section: Formulation Of the Methodsmentioning

confidence: 99%

Section: Formulation Of the Methodsmentioning

confidence: 99%

Section: -64mentioning

confidence: 99%

Section: -64mentioning

confidence: 99%

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A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Valero

Truhlar

2007

J. Phys. Chem. A

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“…The literature on the BeH ground state is extensive; we refer to only a few papers. 15,[67][68][69][70][71][72][73] In the HF model the BeH [X 2 Σ + ] binding energy is larger than the experimental, a rather rare event in molecular computations, even if not too surprising since the variational principle holds for the total energy of the system and not for arbitrary partitioning.…”

Section: Beh [X 2 σ + ] Ground Statementioning

confidence: 99%

Hartree−Fock−Heitler−London Method. 2. First and Second Row Diatomic Hydrides

Corongiu

2006

J. Phys. Chem. A

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The Hartree-Fock-Heitler-London, HF-HL, method is a new ab initio approach which variationally combines the Hartree-Fock, HF, and the Heitler-London, HL, approximations, yielding correct dissociation products. Furthermore, the new method accounts for nondynamical correlation and explicitly considers avoided crossing. With the HF-HL model we compute the ground-state potential energy curves for H2 [1Sigma+g], LiH [X 1Sigma+], BeH [2Sigma+], BH [1Sigma+], CH [2Pi], NH [3Sigma-], OH [2Pi], and FH [1Sigma+], obtaining in average 80% of the experimental binding energy with a correct representation of bond breaking. Inclusion of ionic configurations improves the computed binding energy. The computed dipole moment is in agreement with laboratory data. The dynamical and nondynamical correlation energies for atomic and molecular systems with 2-10 electrons are analyzed. For BeH the avoided crossing of the two lowest [2Sigma+] states is considered in detail. The HF-HL function is proposed as the zero-order reference wave function for molecular systems. To account for the dynamical correlation energy a post-HF-HL technique based on multiconfiguration expansions is presented. We have computed the potential energy curves for H2 [1Sigma+g], HeH [2Sigma+], LiH [X1Sigma+], LiH [A1Sigma+], and BeH [2Sigma+]. The corresponding computed binding energies are 109.26 (109.48), 0.01 (0.01), 57.68 (58.00), 24.19 (24.82), and 49.61 (49.83) kcal/mol, with the experimental values given in parentheses. The corresponding total energies are -1.1741, -3.4035, -8.0695, -7.9446, and -15.2452 hartrees, respectively, the best ab initio variational published calculations, H2 excluded.

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Aspects of the Chemical Energetics of Species with Carbon–Boron Bonds and Related Compounds

Slayden¹,

Liebman²

2020

Patai's Chemistry of Functional Groups

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In this chapter, we discuss selected energetics and thermochemical aspects of species with carbon–boron bonds. Although they lack a carbon–boron bond, atomic boron, its anion, and binary metal borides—the hypothetical alkali metal borides MB—and structurally complex metal borides are briefly introduced. Consideration of species with carbon–boron bonds begins with binary species such as the gas‐phase diatomic BC and the solid B 4 C and proceeds to the highly reactive methyl and phenyl derivatives of univalent borylene, BH. The question of regular behavior as homologous series is addressed for the relatively stable and long‐known classes of compounds, trialkylboranes and carboranes, with their normal (threefold) and higher boron‐coordination numbers. Trivalent boron and nitrogen species are then compared, first as organoboranes and amines, then as their organoborate and ammonium ions, and also as their “dimer” anions and cations. Pyridine borane complexes are likewise discussed and compared with benzene derivatives. Species with boron in the ring, borabenzenes and their amine complexes, are much more poorly understood. However, aromatic derivatives with both boron and nitrogen in the ring have evinced considerable interest, and the derivatives of the isomeric 1,2‐, 1,3‐, and 1,4‐azaborinines are described at some length. The chapter closes with species that contain oxygen along with boron, carbon, and hydrogen. Borane carbonyl (BH 3 CO), boronic acid derivatives, and boroxines are discussed.

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Theory of the Electronic Energy Levels of Simple Hydrides

Cited by 20 publications

References 23 publications

A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

A Diabatic Representation Including Both Valence Nonadiabatic Interactions and Spin−Orbit Effects for Reaction Dynamics

Hartree−Fock−Heitler−London Method. 2. First and Second Row Diatomic Hydrides

Aspects of the Chemical Energetics of Species with Carbon–Boron Bonds and Related Compounds

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