標題: Choice of Optimal Shift Parameter for the Intruder State Removal Techniques in Multireference Perturbation Theory
作者: Chang, Shu-Wei
Witek, Henryk A.
應用化學系
應用化學系分子科學碩博班
Department of Applied Chemistry
Institute of Molecular science
公開日期: 1-十一月-2012
摘要: An extensive critical evaluation of intruder state removal techniques (aka shift techniques) applicable to multireference perturbation theory (MRPT) shows that the magnitude of the shift parameter a does not influence the spectroscopic parameters of diatomics to a significant degree, provided that the shift is chosen to be sufficiently large. In such case, typical variation of spectroscopic parameters over a wide range of shift parameters is smaller than 0.005 angstrom for equilibrium distances, 30 cm(-1) for harmonic vibrational frequencies, and 0.1 eV for dissociation energies. It is found that large values of a not only remove intruder states but they also bring the MRPT energies and properties closer to experimental values. The presented analysis allows us to determine optimal values of the shift parameters to be used in conjunction with various versions of MRPT; these values are recommended to replace the ad hoc values of sigma suggested in MRPT manuals in calculations for diatomics. Transferability of the optimal shift parameters to larger molecular systems and to other basis sets than aug-cc-pVTZ is anticipated but remains to be formally established.
URI: http://dx.doi.org/10.1021/ct2006924
http://hdl.handle.net/11536/20647
ISSN: 1549-9618
DOI: 10.1021/ct2006924
期刊: JOURNAL OF CHEMICAL THEORY AND COMPUTATION
Volume: 8
Issue: 11
起始頁: 4053
結束頁: 4061
顯示於類別:期刊論文


文件中的檔案:

  1. 000311191900008.pdf