Study of localized molecular orbitals using group theory methods and its approach to the many-electron correlation problem. III. Orthogonal bonded functions

✍ Scribed by Taijin Zhou

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 627 KB
• Volume: 14
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540140507

✦ Synopsis

using the group symmetrical localized molecular orbitals (SLhfOs) as configuration-generating orbitals (CGOs) of many-electron wave functions, the symmetry adaptation of many-electron spaces is greatly simplified, and novel orthogonal bonded functions (OBFs), as complete space-and spin-adapted antisymmetrized products, are introduced. The corresponding programs for the solutions of OBFs are developed. 0 1993 by John Wiley 8, Sons, Inc.

Based upon the FORS model, an n-dimensional complete active space (CAS) V,,, invariant under the molecular symmetry group G , is generated, and the CAS is spanned by a set of orthonormal SLMOs: { i l , . . . , i,, . . . , ivL}.lg The corresponding spins are {a, p}. The n SLMOs may be divided into some subsets. Each subset spans an invariant subspace under G and is characterized by given CIL and CIR. CIL and CIR are called the character information of the invariant ~ubspace.'~ 2. Suppose the number of electrons in the CAS is N , and the N-electron function space is spanned by a basis of spin-adapted antisymmetrized products However, it is a common weakness in these approaches that they lack a general and efficient (SAAPs) and classified according to total spin S as well as its x component S,. The V(n, N , S, S,