Extended Koopmans' theorem: Approximate ionization energies from MCSCF wave functions
✍ Scribed by Robert C. Morrison; Guanghua Liu
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 667 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The extended Koopmans' theorem has been implemented using multiconfigurational self‐consistent field wave functions calculated with the GAMESS, HONDO, and SIRIUS programs. The results of illustrative calculations are presented for the molecules HF, H~2~O, NH~3~, CH~4~, N~2~, CO, HNC, HCN, C~2~H~2~, H~2~CO, and B~2~H~6~. The lowest extended Koopmans' theorem ionization potentials agree well within the experimental values and the ionization potentials representing excited states of the ions show some improvements over the Koopmans' theorem values in most cases. The extended Koopmans' theorem is easily implemented and the time required to calculate the ionization energies is insignificant compared to the time required to calculate the wave function of the un‐ionized molecule. © 1992 by John Wiley & Sons, Inc.