A New Size Extensive Multireference Perturbation Theory

作者：Chen Feiwu^*; Fan Zhihui

来源：Journal of Computational Chemistry, 2014, 35(2): 121-129.

DOI：10.1002/jcc.23471

• multireference perturbation theory
• single reference perturbation theory
• Rayleigh-Schrodinger perturbation theory
• MOller-Plesset perturbation theory
• size extensivity-orbital invariance

A new multireference perturbation series is derived based on the Rayleigh-Schrodinger perturbation theory. It is orbitally invariant. Its computational cost is comparable to the single reference MOller-Plesset perturbation theory. It is demonstrated numerically that the present multireference second- and third-order energies are size extensive by two types of supermolecules composed of H-2 and BH monomers. Spectroscopic constants of F2(X1 sigma g+</mml:msubsup>),Cl2(X1<mml:msubsup>sigma g+</mml:msubsup>),<mml:msubsup>C2-</mml:msubsup>(X2<mml:msubsup>sigma g+</mml:msubsup>),<mml:msub>B2(X3<mml:msubsup>sigma g-</mml:msubsup>),and<mml:msubsup>C2+</mml:msubsup>(X4<mml:msubsup>sigma g-</mml:msubsup>) as well as the ground state energies of H2O, NH2, and CH2 at three bond lengths have been calculated with the second multireference perturbation theory. The dissociation behaviors of CH4 and HF have also been investigated. Comparisons with other approximate theoretical models as well as the experimental data have been carried out to show their relative performances.

• 出版日期2014-1-15
• 单位北京科技大学