On the Use of Connected Moments Expansion with Coupled Cluster Reference

International Journal of Molecular Sciences

Jozef Noga¹  Agnes Szabados¹ 

[1] ¹Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, Slovakia ²Structural Chemistry Research Group, Hungarian Academy of Sciences, E¨otv¨os University, POB 32, H-1518 Budapest, Hungary ³Department of Theoretical Chemistry, E¨otv¨os University, POB 32, H-1518 Budapest 112, Hungary

关键词: Electron correlation;    Coupled cluster theory;    Non-iterative corrections;    Connected moments expansion;   

DOI  :  10.3390/i3050508

来源: mdpi

【 摘 要 】

We examine the possibility of introducing a new class of so called noniterative corrections to coupled cluster energies, based on the connected moments expansion (CMX). Approximate Coupled Cluster (CC) wave functions are used as reference states and then the “improved energies” can be formally obtained either by CMX in terms of the moments of CC similarity transformed Hamiltonian, or in CMX of the usual Hamiltonian. Numerical results are given for some model systems that show the superiority of the latter approach.

【 授权许可】

CC BY   
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.