title: Divide-and-Conquer-Type Density-Functional Tight-Binding Molecular Dynamics Simulations of Proton Diffusion in a Bulk Water System.
abstract: The process of proton diffusion in liquid water was investigated using molecular dynamics (MD) simulations, and the total energy and atomic forces were evaluated by the divide-and-conquer-type density-functional tight-binding (DC-DFTB) method. The effectiveness of this approach was confirmed by comparing the computational time of water clusters with conventional treatments. The unit cell employed herein, which contained 523 water molecules and 1 excess proton, was moderately large in comparison with those used in previous studies. The reasonable accuracy obtained by using this unit cell was confirmed by examining the temperature fluctuation. The diffusion coefficients for the vehicular and Grotthuss processes were accurately reproduced by the DC-DFTB-MD simulations with the unit cell containing 523 water molecules. Furthermore, the energy barriers were evaluated from the temperature dependence of the diffusion coefficient for each process. The calculated barrier for Grotthuss diffusion was in good agreement with the experimental value.
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University , Tokyo 169-8555, Japan.|Research Institute for Science and Engineering, Waseda University , Tokyo 169-8555, Japan.|CREST, Japan Science and Technology Agency , Tokyo 102-0075, Japan.|ESICB, Kyoto University , Kyoto 615-8520, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakai
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University , Tokyo 169-8555, Japan.
authors.forename: Aditya Wibawa
authors.initials: AW
authors.lastname: Sakti
authors.affiliation: Research Institute for Science and Engineering, Waseda University , Tokyo 169-8555, Japan.|Department of Theoretical and Computational Molecular Science, Institute for Molecular Science , Okazaki 444-8585, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nishimura