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A modified definition of the zeroth-order Hamiltonian in multiconfigurational perturbation theory (CASPT2)

Ghigo, Giovanni LU ; Roos, Björn LU and Malmqvist, Per-Åke LU (2004) In Chemical Physics Letters 396(1-3). p.142-149
Abstract
A new shifted zeroth-order Hamiltonian is presented, which will be used in second-order multiconfigurational perturbation theory (CASPT2). The new approximation corrects for the systematic error of the original formulation, which led to an relative overestimate of the correlation energy for open shell system, resulting in too small dissociation and excitation energies. Errors in the D, values for 49 diatomic molecules have been reduced with more than 50%. Calculations on excited states of the N-2 and benzene molecules give a similar improvement. (C) 2004 Elsevier B.V. All rights reserved.
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Chemical Physics Letters
volume
396
issue
1-3
pages
142 - 149
publisher
Elsevier
external identifiers
  • wos:000223972300026
  • scopus:8344289249
ISSN
0009-2614
DOI
10.1016/j.cplett.2004.08.032
language
English
LU publication?
yes
id
a7d216d2-c45c-4c67-9aa1-d74336580fe8 (old id 139596)
date added to LUP
2007-07-17 09:57:48
date last changed
2017-12-17 03:58:30
@article{a7d216d2-c45c-4c67-9aa1-d74336580fe8,
  abstract     = {A new shifted zeroth-order Hamiltonian is presented, which will be used in second-order multiconfigurational perturbation theory (CASPT2). The new approximation corrects for the systematic error of the original formulation, which led to an relative overestimate of the correlation energy for open shell system, resulting in too small dissociation and excitation energies. Errors in the D, values for 49 diatomic molecules have been reduced with more than 50%. Calculations on excited states of the N-2 and benzene molecules give a similar improvement. (C) 2004 Elsevier B.V. All rights reserved.},
  author       = {Ghigo, Giovanni and Roos, Björn and Malmqvist, Per-Åke},
  issn         = {0009-2614},
  language     = {eng},
  number       = {1-3},
  pages        = {142--149},
  publisher    = {Elsevier},
  series       = {Chemical Physics Letters},
  title        = {A modified definition of the zeroth-order Hamiltonian in multiconfigurational perturbation theory (CASPT2)},
  url          = {http://dx.doi.org/10.1016/j.cplett.2004.08.032},
  volume       = {396},
  year         = {2004},
}