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Theoretical studies on chemical bonding between Cu(II) and oxygen molecule in type 3 copper proteins
Author(s) -
Saito Toru,
Kataoka Yusuke,
Nakanishi Yasuyuki,
Matsui Toru,
Kitagawa Yasutaka,
Kawakami Takashi,
Okumura Mitsutaka,
Yamaguchi Kizashi
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.22429
Subject(s) - chemistry , copper , diradical , polarizability , molecule , type (biology) , complete active space , density functional theory , computational chemistry , crystallography , chemical physics , molecular physics , atomic physics , physics , basis set , singlet state , excited state , ecology , biology , organic chemistry
We discussed the most stable coordination of O 2 binding in the Cu 2 O 2 core of type 3 copper proteins from a viewpoint of broken‐symmetry (BS) DFT approach. This study put its focus on the active site of both oxy and deoxy form of hemocyanin as an example. We examined four conventional hybrid GGA functional sets that contain different proportion of exact exchange in a range of 20–50% within a BS way. To evaluate their net accuracy, the spin contamination errors caused by the triplet ( S = 1) state on energy and energy gradient in the BS ( S = 0) state were replaced by our approximate spin projection (AP) procedure. We also examined OO stretch vibrational frequencies and Gibbs free energies of O 2 binding with the conductor‐like polarizable continuum model. From the results, UBHandHLYP outperform the other functional sets, indicating that the Cu 2 O 2 core in oxyHc has significant diradical character under AP‐BS approximation. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009