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Extended Dynamically Weighted CASPT2: The Best of Two Worlds
[Image: see text] We introduce a new variant of the complete active space second-order perturbation theory (CASPT2) method that performs similarly to multistate CASPT2 (MS-CASPT2) in regions of the potential energy surface where the electronic states are energetically well separated and is akin to e...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American
Chemical Society
2020
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307887/ https://www.ncbi.nlm.nih.gov/pubmed/32027802 http://dx.doi.org/10.1021/acs.jctc.9b01129 |
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author | Battaglia, Stefano Lindh, Roland |
author_facet | Battaglia, Stefano Lindh, Roland |
author_sort | Battaglia, Stefano |
collection | PubMed |
description | [Image: see text] We introduce a new variant of the complete active space second-order perturbation theory (CASPT2) method that performs similarly to multistate CASPT2 (MS-CASPT2) in regions of the potential energy surface where the electronic states are energetically well separated and is akin to extended MS-CASPT2 (XMS-CASPT2) in case the underlying zeroth-order references are near-degenerate. Our approach follows a recipe analogous to that of XMS-CASPT2 to ensure approximate invariance under unitary transformations of the model states and a dynamic weighting scheme to smoothly interpolate the Fock operator between state-specific and state-average regimes. The resulting extended dynamically weighted CASPT2 (XDW-CASPT2) methodology possesses the most desirable features of both MS-CASPT2 and XMS-CASPT2, that is, the ability to provide accurate transition energies and correctly describe avoided crossings and conical intersections. The reliability of XDW-CASPT2 is assessed on a number of molecular systems. First, we consider the dissociation of lithium fluoride, highlighting the distinctive characteristics of the new approach. Second, the invariance of the theory is investigated by studying the conical intersection of the distorted allene molecule. Finally, the relative accuracy in the calculation of vertical excitation energies is benchmarked on a set of 26 organic compounds. We found that XDW-CASPT2, albeit being only approximately invariant, produces smooth potential energy surfaces around conical intersections and avoided crossings, performing equally well to the strictly invariant XMS-CASPT2 method. The accuracy of vertical transition energies is almost identical to MS-CASPT2, with a mean absolute deviation of 0.01–0.02 eV, in contrast to 0.12 eV for XMS-CASPT2. |
format | Online Article Text |
id | pubmed-7307887 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | American
Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-73078872020-06-23 Extended Dynamically Weighted CASPT2: The Best of Two Worlds Battaglia, Stefano Lindh, Roland J Chem Theory Comput [Image: see text] We introduce a new variant of the complete active space second-order perturbation theory (CASPT2) method that performs similarly to multistate CASPT2 (MS-CASPT2) in regions of the potential energy surface where the electronic states are energetically well separated and is akin to extended MS-CASPT2 (XMS-CASPT2) in case the underlying zeroth-order references are near-degenerate. Our approach follows a recipe analogous to that of XMS-CASPT2 to ensure approximate invariance under unitary transformations of the model states and a dynamic weighting scheme to smoothly interpolate the Fock operator between state-specific and state-average regimes. The resulting extended dynamically weighted CASPT2 (XDW-CASPT2) methodology possesses the most desirable features of both MS-CASPT2 and XMS-CASPT2, that is, the ability to provide accurate transition energies and correctly describe avoided crossings and conical intersections. The reliability of XDW-CASPT2 is assessed on a number of molecular systems. First, we consider the dissociation of lithium fluoride, highlighting the distinctive characteristics of the new approach. Second, the invariance of the theory is investigated by studying the conical intersection of the distorted allene molecule. Finally, the relative accuracy in the calculation of vertical excitation energies is benchmarked on a set of 26 organic compounds. We found that XDW-CASPT2, albeit being only approximately invariant, produces smooth potential energy surfaces around conical intersections and avoided crossings, performing equally well to the strictly invariant XMS-CASPT2 method. The accuracy of vertical transition energies is almost identical to MS-CASPT2, with a mean absolute deviation of 0.01–0.02 eV, in contrast to 0.12 eV for XMS-CASPT2. American Chemical Society 2020-02-06 2020-03-10 /pmc/articles/PMC7307887/ /pubmed/32027802 http://dx.doi.org/10.1021/acs.jctc.9b01129 Text en Copyright © 2020 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. |
spellingShingle | Battaglia, Stefano Lindh, Roland Extended Dynamically Weighted CASPT2: The Best of Two Worlds |
title | Extended Dynamically Weighted CASPT2: The Best of
Two Worlds |
title_full | Extended Dynamically Weighted CASPT2: The Best of
Two Worlds |
title_fullStr | Extended Dynamically Weighted CASPT2: The Best of
Two Worlds |
title_full_unstemmed | Extended Dynamically Weighted CASPT2: The Best of
Two Worlds |
title_short | Extended Dynamically Weighted CASPT2: The Best of
Two Worlds |
title_sort | extended dynamically weighted caspt2: the best of
two worlds |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307887/ https://www.ncbi.nlm.nih.gov/pubmed/32027802 http://dx.doi.org/10.1021/acs.jctc.9b01129 |
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