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Molecular geometry optimization by semiempirical methods using an optimized minimization of electronic and nuclear energies
Author(s) -
Pack George R.,
Goetschel Dudley V.
Publication year - 2009
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.560180721
Subject(s) - energy minimization , maxima and minima , minification , metric (unit) , computation , wave function , function (biology) , matrix (chemical analysis) , convergence (economics) , potential energy , energy (signal processing) , point (geometry) , computational chemistry , mathematics , physics , geometry , chemistry , algorithm , mathematical optimization , mathematical analysis , quantum mechanics , operations management , chromatography , evolutionary biology , economics , biology , economic growth
A method for locating minima on semiempirical potential energy surfaces is proposed. The method utilizes standard variable metric minimization techniques of optimization theory. By relaxing the criterion for convergence of the scf energy, the number of iterations may be substantially reduced for each evaluation of the semiempirical energy. Although this leads to an increase in the total number of scf calculations required for the location of the minimum energy geometry, the total number of matrix diagonalizations is decreased. By using the density matrix from one scf calculation as the starting point for the next the quality of the wave function gradually increases along the optimization route. Numerous examples are presented, demonstrating a savings in computation time with no loss in accuracy of the final wave function or geometry.