title: Large-Scale Quantum-Mechanical Molecular Dynamics Simulations Using Density-Functional Tight-Binding Combined with the Fragment Molecular Orbital Method.
abstract: The fully analytic gradient is developed for density-functional tight-binding (DFTB) combined with the fragment molecular orbital (FMO) method (FMO-DFTB). The response terms arising from the coupling of the electronic state to the embedding potential are derived, and the gradient accuracy is demonstrated on water clusters and a polypeptide. The radial distribution functions (RDFs) obtained with FMO-DFTB are found to be similar to those from conventional DFTB, while the computational cost is greatly reduced; for 256 water molecules one molecular dynamics (MD) step takes 73.26 and 0.68 s with full DFTB and FMO-DFTB, respectively, showing a speed-up factor of 108. FMO-DFTB/MD is applied to 100 ps MD simulations of liquid hydrogen halides and is found to reproduce experimental RDFs reasonably well.
authors.affiliation: Department of Chemistry, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.|Fukui Institute for Fundamental Chemistry, Kyoto University , 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nishimoto
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology , B-62 4259 Nagatsuta-cho, Midoriku, Yokohama 226-8501, Japan.|RIKEN, Research Cluster for Innovation , Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Nakata
authors.affiliation: Research Center for Computational Design of Advanced Functional Materials (CD-FMat), 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: Department of Chemistry, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.|Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Stephan
authors.initials: S
authors.lastname: Irle