A new internally contracted multi-reference configuration interaction method

被引:279
|
作者
Shamasundar, K. R. [1 ]
Knizia, Gerald [1 ]
Werner, Hans-Joachim [1 ]
机构
[1] Univ Stuttgart, Inst Theoret Chem, D-70569 Stuttgart, Germany
来源
JOURNAL OF CHEMICAL PHYSICS | 2011年 / 135卷 / 05期
关键词
configuration interactions; orbital calculations; organic compounds; tensors; 2ND-ORDER PERTURBATION-THEORY; CONSISTENT ELECTRON PAIRS; GENERAL COUPLED-CLUSTER; BASIS-SET CONVERGENCE; QUANTUM-CHEMISTRY; FOCK SPACE; CORRELATED CALCULATIONS; ABSORPTION-SPECTRUM; AB-INITIO; WAVE;
D O I
10.1063/1.3609809
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We present a new internally contracted multi-reference configuration interaction (MRCI) method which, at the same time, efficiently handles large active orbital spaces, long configuration expansions, and many closed-shell orbitals in the reference function. This is achieved by treating the closed-shell orbitals explicitly, so that all required coupling coefficients and density matrices only depend on active orbital labels. As a result, closed-shell orbitals are handled as efficiently as in a closed-shell single-reference program, and this opens up the possibility to perform high-accuracy MRCI calculations for much larger molecules than before. The enormously complex equations are derived using a new domain-specific computer algebra system and semi-automatically implemented using a newly developed integrated tensor framework. The accuracy and efficiency of the MRCI method is demonstrated with applications to dioxygen-copper complexes with different ligands, some of which involve more than 30 atoms, and to spin-state splittings of ferrocene. (C) 2011 American Institute of Physics. [doi:10.1063/1.3609809]
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页数:17
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