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Inclusion of relativistic effects into ZDO methods. IV. Relativistic CNDO /1
Author(s) -
Boča Roman
Publication year - 1990
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.560370302
Subject(s) - cndo/2 , relativistic quantum chemistry , spinor , physics , chemistry , open shell , atomic physics , complete active space , basis set , quantum mechanics , molecule
A relativistic, four‐component version of the CNDO (complete neglect of differential overlap) method is introduced. This method spans the class of zero‐differential‐overlap approximation and it utilizes a nonempirical parametrization based on results of atomic Dirac‐Fock calculations. The spin‐orbit splitting is included implicitly using the relativistic basis set which distinguishes Slater‐type functions of the lower and higher component spinors. The method is applicable to closed‐shell as well as to open‐shell systems. The actual version used is the R ‐ CNDO /1 χ with a variable scaling approach. Applications to molecular geometries, ionization potentials, and energies of spin‐orbit splitting are demonstrated for AH, AH 2 , AH 3 , MH, InX, and HgI 2 molecules at the self‐consistent‐field level as well as in the second order of the many‐body perturbation theory.