Influence of the choice of projection manifolds in the CASPT2 implementation
(2017) In Molecular Physics 115(17-18). p.2077-2085- Abstract
The Complete Active Space Second-Order Perturbation Theory (CASPT2) is well-established as a high-accuracy electronic structure method. It was originally implemented in the early 1990s to an efficient computer code in the molcas program suite, and this implementation has been extensively used as a standard tool. Here, we report a comparison of it against two independent computer-aided implementations of the CASPT2 method, revealing that the CASPT2 energies provided by the original code of molcas (version 8 or earlier) are inconsistent with the predictions of the lately developed computer-aided implementations. It is shown that this error is associated with the projections of the first-order equation onto the fully internally contracted... (More)
The Complete Active Space Second-Order Perturbation Theory (CASPT2) is well-established as a high-accuracy electronic structure method. It was originally implemented in the early 1990s to an efficient computer code in the molcas program suite, and this implementation has been extensively used as a standard tool. Here, we report a comparison of it against two independent computer-aided implementations of the CASPT2 method, revealing that the CASPT2 energies provided by the original code of molcas (version 8 or earlier) are inconsistent with the predictions of the lately developed computer-aided implementations. It is shown that this error is associated with the projections of the first-order equation onto the fully internally contracted multireference bases which are partially inconsistent between the left- and right-hand sides. The degree of the errors is assessed by performing illustrative CASPT2 calculations. The errors in total CASPT2 energies are demonstrated to be negligible relative to chemical accuracy in many cases, while there is a difficult case where they may substantially alter chemical description. The incorporation of the consistent projections into molcas has been carried out, which is available in the version 8 sp1.
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- author
- Yanai, Takeshi ; Kurashige, Yuki ; Saitow, Masaaki ; Chalupský, Jakub ; Lindh, Roland LU and Malmqvist, Per Åke LU
- organization
- publishing date
- 2017-09-17
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- CASPT2, computer-aided programming, MOLCAS, Multireference theory
- in
- Molecular Physics
- volume
- 115
- issue
- 17-18
- pages
- 2077 - 2085
- publisher
- Taylor & Francis
- external identifiers
-
- scopus:85007311372
- wos:000408727700010
- ISSN
- 0026-8976
- DOI
- 10.1080/00268976.2016.1271152
- language
- English
- LU publication?
- yes
- id
- af2e5482-48bd-4ca9-8ff6-9869213e2d38
- date added to LUP
- 2017-01-13 11:19:20
- date last changed
- 2025-01-12 19:25:34
@article{af2e5482-48bd-4ca9-8ff6-9869213e2d38,
abstract = {{<p>The Complete Active Space Second-Order Perturbation Theory (CASPT2) is well-established as a high-accuracy electronic structure method. It was originally implemented in the early 1990s to an efficient computer code in the molcas program suite, and this implementation has been extensively used as a standard tool. Here, we report a comparison of it against two independent computer-aided implementations of the CASPT2 method, revealing that the CASPT2 energies provided by the original code of molcas (version 8 or earlier) are inconsistent with the predictions of the lately developed computer-aided implementations. It is shown that this error is associated with the projections of the first-order equation onto the fully internally contracted multireference bases which are partially inconsistent between the left- and right-hand sides. The degree of the errors is assessed by performing illustrative CASPT2 calculations. The errors in total CASPT2 energies are demonstrated to be negligible relative to chemical accuracy in many cases, while there is a difficult case where they may substantially alter chemical description. The incorporation of the consistent projections into molcas has been carried out, which is available in the version 8 sp1.</p>}},
author = {{Yanai, Takeshi and Kurashige, Yuki and Saitow, Masaaki and Chalupský, Jakub and Lindh, Roland and Malmqvist, Per Åke}},
issn = {{0026-8976}},
keywords = {{CASPT2; computer-aided programming; MOLCAS; Multireference theory}},
language = {{eng}},
month = {{09}},
number = {{17-18}},
pages = {{2077--2085}},
publisher = {{Taylor & Francis}},
series = {{Molecular Physics}},
title = {{Influence of the choice of projection manifolds in the CASPT2 implementation}},
url = {{http://dx.doi.org/10.1080/00268976.2016.1271152}},
doi = {{10.1080/00268976.2016.1271152}},
volume = {{115}},
year = {{2017}},
}