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Applicability of quasi‐degenerate many‐body perturbation theory to the ground state of the F 2 molecule
Author(s) -
Mášik Jozef,
Hubač Ivan,
Mach Pavel
Publication year - 1995
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560530306
Subject(s) - degenerate energy levels , ground state , valence (chemistry) , basis set , atomic physics , complete active space , physics , perturbation (astronomy) , quantum mechanics , perturbation theory (quantum mechanics) , molecule , electron , fermi gamma ray space telescope , chemistry
The ground‐state potential energy curve of the F 2 molecule as well as spectroscopic constants were calculated by means of the second‐order quasi‐degenerate many‐body perturbation theory within a full (eight) valence orbital space using a DZP basis set. The problem encountered with a large number of valence electrons is avoided by a proper redefinition of the Fermi vacuum. A comparison with other related multireference techniques is also provided. © 1995 John Wiley & Sons, Inc.