Introduction of n-electron valence states for multireference perturbation theory
Introduction of n-electron valence states for multireference perturbation theory
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DOI：
10.1063/1.1361246
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发表时间：
2001-06-15
影响因子：
4.4
通讯作者：
Malrieu, JP
中科院分区：
文献类型：
--
作者：
Angeli, C;Cimiraglia, R;Malrieu, JP
本工作从一个完全活性空间（CAS）零级波函数给出了三个二阶微扰展开式，它们对于分子解离是严格可加的且无闯入态。它们因外空间微扰子的收缩程度不同而有所差异。提出了两种零级哈密顿量，它们都是双电子的，包含了活性轨道中电子之间的相互作用，因此在零级波函数和外空间之间引入了合理的平衡。使用将活性电子置于固定核场的戴尔哈密顿量以及一种部分收缩的形式体系似乎是一种有前景的折衷方案。该形式体系可推广到作为广义活性空间（GAS）一部分的多参考空间。本文所发展的最简单变体的一些测试应用说明了它的潜力。（C）2001美国物理学会。
The present work presents three second-order perturbative developments from a complete active space (CAS) zero-order wave function, which are strictly additive with respect to molecular dissociation and intruder state free. They differ by the degree of contraction of the outer-space perturbers. Two types of zero-order Hamiltonians are proposed, both are bielectronic, incorporating the interactions between electrons in the active orbitals, therefore introducing a rational balance between the zero-order wave function and the outer-space. The use of Dyall's Hamiltonian, which puts the active electrons in a fixed core field, and of a partially contracted formalism seems a promising compromise. The formalism is generalizable to multireference spaces which are parts of a GAS. A few test applications of the simplest variant developed in this paper illustrate its potentialities. (C) 2001 American Institute of Physics.