Acta Phys. -Chim. Sin. ›› 2007, Vol. 23 ›› Issue (09): 1360-1364.doi: 10.1016/S1872-1508(07)60072-2

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Numerical Study on the Size Consistency of the Multireference Perturbation Theory

CHEN Fei-Wu   

  1. Department of Chemistry, University of Science and Technology Beijing, Beijing 100083, P. R. China
  • Received:2007-05-15 Revised:2007-07-13 Published:2007-09-06
  • Contact: CHEN Fei-Wu

Abstract: The size consistency of the multireference perturbation theory and multireference singly-excited and doubly-excited configuration interaction (MRSDCI) was investigated numerically with three super-molecular models composed of H2, He, and LiH monomers separated by a large distance. A small full configuration interaction was performed first over the model space and then multireference perturbation calculations were carried out. Numerical results demonstrated that the previously derived size consistent multireference second-order perturbation theory was size consistent with respect to the above three super-molecules. Its accuracy relative to the full configuration interaction (CI) was also discussed. Size consistent error of two sets of the multireference second-order and third-order perturbation theories as well as MRSDCI were studied and compared.

Key words: Size consistency, Multireference perturbation theory, Numerical study


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