Topological Control of Molecular Orbital Theory: A Comparison of µ2-Scaled Hückel Theory and Restricted Hartree-Fock Theory for Boranes and Carboranes

Hartree Fock (HF) and Density Functional Theory (DFT) have been commonly used to model chemical problems. This study uses the Molecular Orbital Theory (MOT) to evaluate the electronic structure of five diatomic molecules generated by HF and DFT calculations. The evaluation provides an explanation of how the orbitals of a molecule come to be and how this affects the calculation of the physical quantities of the molecule. The evaluation is obtained after comparing the orbital wave functions calculated by MOT, HF, and DFT. This study found that the nature of the Highest Occupied Molecular Orbital (HOMO) of a molecule is determined by the valence orbital properties of the constituent atoms. This HOMO property greatly influences the precision of calculating the molecular electric dipole moment. This shows the importance of understanding the orbital properties of a molecule formed from the HF and DFT calculations

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Huckel theory with overlap for the three-electron bond

Australian Journal of Chemistry ◽

10.1071/ch9780199 ◽

1978 ◽

Vol 31 (1) ◽

pp. 199 ◽

Cited By ~ 7

Author(s):

RD Harcourt

Keyword(s):

Molecular Orbital ◽

Stabilization Energy ◽

Molecular Orbital Theory ◽

Orbital Theory ◽

Constructive Interference ◽

Hückel Theory ◽

Resonance Stabilization ◽

Hückel Molecular Orbital Theory

For a three-electron bond between two equivalent atoms, Huckel molecular orbital theory with overlap generates a resonance stabilization energy which is formally identical to that obtained from molecular orbital theory when electronic repulsions are included and the Mulliken approximation (ab ≈ ½S(aa+bb)) is invoked. The latter energy is the constructive interference energy.

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An abinitio molecular orbital study of isomers on the C2NH5+• and C2NH5 surfaces

Canadian Journal of Chemistry ◽

10.1139/v84-151 ◽

1984 ◽

Vol 62 (5) ◽

pp. 922-925 ◽

Cited By ~ 8

Author(s):

Min H. Lien ◽

Alan C. Hopkinson

Keyword(s):

Molecular Orbital ◽

Single Point ◽

Radical Cations ◽

Basis Set ◽

Molecular Orbital Theory ◽

Orbital Theory ◽

Hartree Fock ◽

Theory Structure ◽

Molecular Orbital Study ◽

Orbital Study

The structures and relative energies of seven possible C2NH5+•isomers have been calculated using abinitio molecular orbital theory. Structure optimisations have been performed with a 4-31G basis set, using both the restricted (RHF) and unrestricted (UHF) Hartree–Fock methods. The optimum geometries were then used for single point calculations using the 6-31G* basis set. The relative energies are 1 < 7 < 5 < 3 ≈ 2 ≈ 6 < 4. This order is the same, with the exception of 6, as for isomers on the C2H4O+•surface and the relative energies are very similar to those on the C2H4O+• surface. The structures of the radical cations C2NH5+• are compared with those of the neutral molecules C2NH5.

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