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Symmetry aspects of diatomics‐in‐molecules (DIM) calculations. II. Construction of symmetry‐adapted diatomic fragment subspaces
Author(s) -
Vojtík Jan
Publication year - 1985
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560280623
Subject(s) - diatomic molecule , linear subspace , symmetry (geometry) , fragment (logic) , polyatomic ion , spin (aerodynamics) , operator (biology) , quantum mechanics , physics , chemistry , mathematics , molecule , geometry , algorithm , biochemistry , repressor , gene , transcription factor , thermodynamics
A new general procedure is presented for the construction of symmetry adapted diatomic fragment sub‐spaces of spin‐adapted polyatomic DIM bases obtained by direct diagonalization of the polyatomic spin‐square operator. The spin part of the construction is accomplished by the diagonalization in the DIM basis of the diatomic spin‐square operators. The spatial part of relevant transformations is given in terms of quantum numbers of the constituent atomic functions. Simple expressions for the spatial symmetry and spin designation of the resulting symmetry‐adapted diatomic fragment states are obtained. Special attention is paid to consistent phases of diatomic fragment functions corresponding to equivalent fragments. The approach eliminates such mental operations from the construction of symmetry‐adapted diatomic fragment subspaces which are difficult to formulate in a way suitable for straightforward computer implementation.