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Molecular symmetry and closed-shell SCF calculations. I

✍ Scribed by Michel Dupuis; Harry F. King

Publisher
John Wiley and Sons
Year
1977
Tongue
English
Weight
658 KB
Volume
11
Category
Article
ISSN
0020-7608

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✦ Synopsis

Abstract

For efficient integral evaluation, orbital basis functions are grouped into shells and integrals into blocks in the recently developed SCF program Hondo. This shell structure is ideally suited to the scheme of Dacre and Elder for using point group symmetry. An entire block of two‐electron integrals is eliminated if it is symmetrically equivalent to another block with a higher index (four label). Using the “petite list” of blocks of integrals, a skeleton Fock matrix is formed from which the true Fock matrix is generated by “symmetrization.” We prove two theorems which provide a clear and rigorous justification for this version of the Dacre–Elder procedure. We compare SCF calculations on the phosphorus molecule using T~d~ symmetry with those using various subgroups of T~d~. The number of integrals computed is found to be approximately inversely proportional to the order of the group. Integral evaluation time and SCF iteration time are each linear functions of the number of integrals. The computer spends a negligible amount of time in executing symmetry‐related code, and the human effort involved is little more than picking the appropriate Schönflies symbol for the molecule.

📜 SIMILAR VOLUMES

Use of molecular symmetry in SCF calcula
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✍ M. Elder 📂 Article 📅 1973 🏛 John Wiley and Sons 🌐 English ⚖ 550 KB

## Abstract A method is described whereby molecular symmetry properties may be used to reduce the numbers of one‐ and two‐electron integrals that need to be calculated and stored in the course of a molecular SCF calculation. The method is a generalization of a previously reported procedure, extendi

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