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Optimization of strong and weak coordinates
Author(s) -
Swart Marcel,
Matthias Bickelhaupt F.
Publication year - 2006
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.21049
Subject(s) - hessian matrix , log polar coordinates , bipolar coordinates , action angle coordinates , delocalized electron , computation , parabolic coordinates , function (biology) , state (computer science) , set (abstract data type) , generalized coordinates , matrix (chemical analysis) , orthogonal coordinates , geometry , computational chemistry , mathematics , physics , algorithm , computer science , chemistry , quantum mechanics , chromatography , evolutionary biology , biology , programming language
We present a new scheme for the geometry optimization of equilibrium and transition state structures that can be used for both strong and weak coordinates. We use a screening function that depends on atom‐pair distances to differentiate strong coordinates from weak coordinates. This differentiation significantly accelerates the optimization of these coordinates, and thus of the overall geometry. An adapted version of the delocalized coordinates setup is used to generate automatically a set of internal coordinates that is shown to perform well for the geometry optimization of systems with weak and strong coordinates. For the Baker test set of 30 molecules, we need only 173 geometry cycles with PW91/TZ2P calculations, which compares well with the best previous attempts reported in literature. For the localization of transition state structures, we generate the initial Hessian matrix, using appropriate force constants from a database. In this way, one avoids the explicit computation of the Hessian matrix. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006