Multiconfigurational SCF approach for high-symmetry molecules and its applications to fullerene trianion
✍ Scribed by Victor A. Kuprievich
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 195 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
A symmetry-adapted multiconfiguration self-consistent field MC SCF approach aimed at calculations of high-symmetry molecules is proposed. The selfconsistency procedure applicable to the molecular terms of any symmetry and multiplicity is developed. It holds the symmetry transformation properties of varied molecular orbitals, thus taking advantage of the relationships within the set of two-electron integrals through molecular invariants. For orbital optimization, a unified coupling operator is constructed on the basis of the pseudosecular method providing for efficient convergence to energy minimum. Based on the group-theory technique, computer codes have been developed for straightforward determination of the invariant expansions for Ž . two-electron integrals and configuration interaction CI matrix elements. Calculated in this way, the expansion coefficients are presented for the three-electron states that originate from joint t and t shells of an icosahedral fullerene C , the case important 1u 1 g 60 for the calculations of anion C 3y representing the charge state of the fullerene molecule 60 in the superconducting ionic solids K C or Rb C . The results of MC SCF calculations 3 60 3 60
for lowest quasi--electronic states of C 3y are discussed.