This article describes the numerical application of projection operators to restore the symmetry of molecular orbitals in self-consistent field (SCF) calculations when the symmetry is lost because of degeneracy or near degeneracy. The application of projection operators is particularly useful in cas
A treatment of symmetry in MO calculations
✍ Scribed by H.H Jaffé; R.L Ellis
- Publisher
- Elsevier Science
- Year
- 1974
- Tongue
- English
- Weight
- 768 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0021-9991
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📜 SIMILAR VOLUMES
It is shown by a symmetry argument that the band gap in a symmetric polyene must be zero in the restricted single determinant approximation. Spurious band gaps can arise in SCF calculations when the symmetry of the lattice is not refixted in the lattice sums. The consequences of this symmetry probIe
The product of two Gaussians having different centers is itself a one-center Gaussian, thus multicenter integrals with a Cartesian Gaussian basis can be reduced to one-center integrals. Recurrence relations for overlap integrals and Ž . electron repulsion integrals ERIs are derived at these centers.
The symmetry orbital tensor SOT method, which makes full use of symmetries in all point groups and can be applied to the self-consistent field Ž . SCF and post-SCF calculations, is introduced. The principal feature of this Ž . method is the definition of the symmetry orbitals SOs . Any element in a
## 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