Analytical Gradients for the MSINDO-sCIS and MSINDO-UCIS Method: Theory, Implementation, Benchmarks, and Examples

详细信息    查看全文

• 作者：Immanuel Gadaczek ; Katharina Krause ; Kim Julia Hintze ; Thomas Bredow
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2012
• 出版时间：March 13, 2012
• 年：2012
• 卷：8
• 期：3
• 页码：986-996
• 全文大小：348K
• 年卷期：v.8,no.3(March 13, 2012)
• ISSN：1549-9626

文摘

Analytical expressions for the sCIS (scaled configuration interaction singles) and UCIS (unrestricted CIS) energy gradients are presented for the semiempirical method MSINDO. The theoretical background of the derivation of the analytical gradients is presented, and the implementation into the MSINDO program package is described. The computational efficiency of the underlying Z-vector method is greatly enhanced by making use of the transpose-free quasiminimal residual (TFQMR) algorithm. Benchmark timing tests are compared to the widely used TD-B3LYP approach. For a statistical evaluation of the accuracy of MSINDO-sCIS, geometry optimizations are performed for a small set of organic molecules in selected excited states. The obtained results are compared to CASPT2 and TD-B3LYP/TZVP. In order to demonstrate the applicability of the present approach to periodic systems within the cyclic cluster model, we present first calculations of the excited state structure of ethyne adsorbed on the NaCl (100) surface.