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Modified virtual orbitals of Hartree–Fock method in calculation of second-order perturbation energy

✍ Scribed by Eiko Hiroike

Publisher
John Wiley and Sons
Year
1980
Tongue
English
Weight
298 KB
Volume
18
Category
Article
ISSN
0020-7608

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✦ Synopsis

Abstract

An advantage of modified virtual orbitals of Hartree–Fock method is discussed in the calculation of the second‐order perturbation energy. All the modified virtual orbitals can be fitted for the intermediate virtual states in the perturbation expansion, only if the molecular orbitals are expanded in terms of infinite basis functions and the set of molecular orbitals is infinite and complete. If the molecular orbitals are expanded in terms of finite basis functions, only the modified virtual orbitals with lower energies are appropriate to describe the intermediate virtual states, but the modified virtual orbitals with higher energies become inadequate. To explain the usefulness of the modified virtual orbitals, the calculation by the modified Hartree–Fock method without CI are compared with the calculation by the traditional Hartree–Fock method with complete CI.

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