Premium
Developments in the n ‐electron valence state perturbation theory
Author(s) -
Angeli Celestino,
Borini Stefano,
Cavallini Alex,
Cestari Mirko,
Cimiraglia Renzo,
Ferrighi Lara,
Sparta Manuel
Publication year - 2005
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.20831
Subject(s) - degenerate energy levels , valence (chemistry) , rydberg formula , quantum mechanics , perturbation theory (quantum mechanics) , perturbation (astronomy) , physics , electron , poincaré–lindstedt method , wave function , quantum , rydberg atom , atomic physics , theoretical physics , ionization , ion
A short summary of the n‐ electron valence state perturbation theory (NEVPT) is provided, and the defects inherent in cases of quasi‐degeneration are underscored. A new version of the theory, called QD‐NEVPT, based on quasi‐degenerate perturbation theory, is presented. The new theory introduces an effective interaction among the zero‐order wave functions and overcomes the difficulties of state‐specific NEVPT. An application concerning the interaction among the π → π* and Rydberg singlets of formaldehyde is presented. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006