title: Unrestricted density functional theory based on the fragment molecular orbital method for the ground and excited state calculations of large systems.
abstract: We extended the fragment molecular orbital (FMO) method interfaced with density functional theory (DFT) into spin unrestricted formalism (UDFT) and developed energy gradients for the ground state and single point excited state energies based on time-dependent DFT. The accuracy of FMO is evaluated in comparison to the full calculations without fragmentation. Electronic excitations in solvated organic radicals and in the blue copper protein, plastocyanin (PDB code: 1BXV), are reported. The contributions of solvent molecules to the electronic excitations are analyzed in terms of the fragment polarization and quantum effects such as interfragment charge transfer.
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Nakata
authors.affiliation: NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: Dmitri G
authors.initials: DG
authors.lastname: Fedorov
authors.affiliation: RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yokojima
authors.affiliation: Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitaura
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Sakurai
authors.affiliation: RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D015394:Molecular Structure; D010970:Plastocyanin / Q000737:chemistry*; D011487:Protein Conformation; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D046940:Synechococcus / Q000737:chemistry
chemical_list: D012997:Solvents; D010970:Plastocyanin