TY - JOUR
T1 - A Practical Valence Bond Method
T2 - A Configuration Interaction Method Approach with Perturbation Theoretic Facility
AU - Song, Lingchun
AU - Wu, Wei
AU - Zhang, Qianer
AU - Shaik, Sason
PY - 2004/3
Y1 - 2004/3
N2 - The previously developed valence bond configuration interaction (VBCI) method (Wu, W.; Song, L.; Cao, Z.; Zhang, Q.; Shaik, S., J. Phys. Chem. A, 2002, 105, 2721) that borrows the general CI philosophy of the MO theory, is further extended in this article, and its methodological features are improved, resulting in three accurate and cost-effective procedures: (a) the effect of quadruplet excitation is incorporated using the Davidson correction, such that the new procedure reduces size consistency problems, with due improvement in the quality of the computational results, (b) A cost-effective procedure, named VBCI(D, S), is introduced. It includes doubly excited structures for active electrons and singly excited structures for inactive pairs. The computational results of VBCI(D, S) match those of VBCISD with much less computational effort than VBCISD. (c) Finally, a second-order perturbation theory is utilized as a means of configuration selection, and lead to considerable reduction of the computational cost, with little or no loss in accuracy. Applications of the new procedures to bond energies and barriers of chemical reactions are presented and discussed.
AB - The previously developed valence bond configuration interaction (VBCI) method (Wu, W.; Song, L.; Cao, Z.; Zhang, Q.; Shaik, S., J. Phys. Chem. A, 2002, 105, 2721) that borrows the general CI philosophy of the MO theory, is further extended in this article, and its methodological features are improved, resulting in three accurate and cost-effective procedures: (a) the effect of quadruplet excitation is incorporated using the Davidson correction, such that the new procedure reduces size consistency problems, with due improvement in the quality of the computational results, (b) A cost-effective procedure, named VBCI(D, S), is introduced. It includes doubly excited structures for active electrons and singly excited structures for inactive pairs. The computational results of VBCI(D, S) match those of VBCISD with much less computational effort than VBCISD. (c) Finally, a second-order perturbation theory is utilized as a means of configuration selection, and lead to considerable reduction of the computational cost, with little or no loss in accuracy. Applications of the new procedures to bond energies and barriers of chemical reactions are presented and discussed.
KW - Configuration interaction method
KW - Perturbation theory
KW - Valence bond method
UR - http://www.scopus.com/inward/record.url?scp=1442281412&partnerID=8YFLogxK
U2 - 10.1002/jcc.10382
DO - 10.1002/jcc.10382
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:1442281412
SN - 0192-8651
VL - 25
SP - 472
EP - 478
JO - Journal of Computational Chemistry
JF - Journal of Computational Chemistry
IS - 4
ER -