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Geometry optimization method based on approximate spin projection and its application to F 2 , CH 2 , CH 2 OO, and active site of urease
Author(s) -
Kitagawa Yasutaka,
Saito Toru,
Ito Masahide,
Nakanishi Yasuyuki,
Shoji Mitsuo,
Koizumi Kenichi,
Yamanaka Shusuke,
Kawakami Takashi,
Okumura Mitsutaka,
Yamaguchi Kizashi
Publication year - 2007
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.21456
Subject(s) - energy minimization , geometry , spin (aerodynamics) , active site , molecule , projection (relational algebra) , chemistry , urease , physics , molecular physics , computational chemistry , mathematics , thermodynamics , algorithm , biochemistry , enzyme , organic chemistry
A new geometry optimization method based on an approximate spin projection (AP) procedure is proposed to eliminate a spin contamination effect in an optimized structure on a low spin (LS) state of a broken symmetry (BS) method. First, an energy gradient with the AP (AP gradient) is derived and it is applied to the geometry optimization of F 2 , CH 2 , and CH 2 OO in order to obtain their structures without the spin contamination. The optimization method corrects HCH angle of the CH 2 about 10° in comparison with the BS method, and indicates that the spin contamination in optimized geometry of the BS LS states is considerably large. Next, an active site of Urease that consists of two Ni(II) ions is optimized by the AP method. The result indicates that structure of the active site is sensitive to a water molecule called W3. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007