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Selected excitation for CAS‐SDCI calculations
Author(s) -
Bories Benoît,
Maynau Daniel,
Bonnet MarieLaure
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20588
Subject(s) - atomic orbital , excitation , wave function , polyene , dimension (graph theory) , space (punctuation) , locality , range (aeronautics) , function (biology) , atomic physics , physics , statistical physics , computer science , chemistry , quantum mechanics , mathematics , materials science , pure mathematics , organic chemistry , evolutionary biology , composite material , biology , operating system , electron , linguistics , philosophy
A new selected‐configuration interaction method is proposed, based on the use of local orbitals. A corresponding code has been written, which is devoted to CI calculations of rather large systems (about 50–100 carbon‐like atoms). Taking advantage of the locality, and then of the fact that interactions vanish when the distance is large, the dimension of the CI space is largely reduced. The determinants that would be created by long range excitations are expected to have a small weight in the wave function and are therefore eliminated. This selected excitation CI space is particularly suited for large molecules. It is tested on large polyene chains and on a transition metal complex. For large enough systems, the CPU time saving is important and, what is more noticeable, calculations that were impossible to perform without selection are feasible in this approach. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 632–643, 2007