ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Frozen-core calculations on the (He) 2s22p6 - 1S state of the F- ion and the (Ar) 3d44s2 - 5D state of the Cr atom, obtained with differently reduced basis sets and different core-projection schemes, are presented and compared with the corresponding all-electron results in order to analyze the behavior of the core projection under these circumstances. Severe truncation of the valence basis set can give frozen-core results noticeably deviated from the all electron values if the regular projection (projection factors xg = 2.0) is adopted. Much better results are obtained in these cases if a softer projection (xg = 1.0) is used for those core orbitals having high electronic density in regions where the valence basis set has low flexibility. In these circumstances the expectation value of the core projector becomes a nonvanishing correction to the valence energy because the core-valence orthogonality is incomplete after core projection.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560310610
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