Topic
Molecular orbital theory
About: Molecular orbital theory is a research topic. Over the lifetime, 4537 publications have been published within this topic receiving 251469 citations. The topic is also known as: molecular orbital method & MO theory.
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TL;DR: In this article, the authors used perturbation molecular orbital theory to show that the phase of each double bond that meets at the ethylene has necessarily the minus sign in HOMO and LUMO.
Abstract: Classical valence theory suggests the existence of strongly localized bonds (double bonds), i.e., of ethylene-like molecules, in benzenoid hydrocarbons (molecular graphs Bs); such an 'ethylene' is an edge in a hexagon that contacts with three hexagon faces in B. The phase of a bond is defined as the sign either plus for bonding or minus for antibonding. By use of perturbation molecular orbital theory we conclude that the phase of each bond that meets at the ethylene has necessarily the minus sign in HOMO of B; the bond phase alters in HOMO and LUMO of B.
TL;DR: The rotational potential surfaces of formic anhydride and divinyl ether have been investigated using ab initio molecular orbital theory with minimal and extended basis sets and a flexible rotor geometric model.
Abstract: The rotational potential surfaces of formic anhydride and divinyl ether have been investigated using ab initio molecular orbital theory with minimal and extended basis sets and a flexible rotor geometric model. For formic anhydride, the favoured conformation is planar cis-trans (IB), with additional minima corresponding to planar cis-cis (IA) and trans-trans (IC) structures; these lie. respectively, about 1–3 and 3–7 kcal mol−1 above the cis-trans structure. The preferred conformation for divinyl ether is non-planar with C1 symmetry, corresponding to a distortion of the cis-trans structure (IIB). Other minima are found for the planar C2v cis-trans structure (IIC) and for a non-planar structure with C2 symmetry near to cis-cis (IIA). These are predicted to have energies 0.7 and 2.4 kcal mol−1, respectively, higher than the preferred C1 structure.
TL;DR: In this paper, a semi-empirical molecular orbital method is proposed which draws a formal link with Xα atomic calculations, which permits use of the Slater transition state and also calculation of total energies.
Abstract: A new semiempirical molecular orbital method is proposed which draws a formal link with Xα atomic calculations. The method permits use of the Slater transition state and also calculation of total energies.
01 Jan 2012
TL;DR: The quantum chemistry of solids mainly deals with those physical and chemical properties of the solids that depend on the electronic structure as discussed by the authors, which is the main subject of this paper.
Abstract: The quantum chemistry of solids mainly deals with those physical and chemical properties of solids that depend on the electronic structure.
TL;DR: In this paper, the Roothaan-Bagus method for atoms with one open fn-shell was applied to calculate energy values for lanthanide atoms in the ground and excited states.
Abstract: Application of the Roothaan-Bagus method (Hartree-Fock atomic theory) for atoms with one open fn-shell is considered. Energy values for lanthanide atoms in the ground and excited states are calculated by minimization methods of the first and second orders within the limits of Roothaan-Hartree-Fock atomic theory using orbital exponents of Slater-type atomic orbitals.