A Crystal Structure Analysis of Materials by Molecular Dynamics Simulations

In this study, we have investigated the molecular dynamics method for new material design. We have developed a molecular dynamics simulator applicable to general purposes in material science, and have applied this simulator to antiferroelectric liquid crystal, aluminum phosphate crystal, and the crystals of synthetic sugar-based bolaamphiphiles to make clear the structure and properties of these materials on the atomic scale. In Section, we have described theoretical bases of molecular dynamics calculation such as statistical ensembles, equations of motion and periodic boundary condition, and numerical integration for equation of motion and the potential functions expressed interatomic and intermolecular interactions which play important role in molecular dynamics simulation of real materials. In Section 3, we have described the mechanism of reversible phase transition between crystal and amorphous state of AlPO₄ and new phase(��) of AlPO₄ which is composed of PO₆ and AlO₆ at 2500K and 58GPa. In Section 4, we have described molecular conformations and crystal packing of MHPOBC (4-[(S)-1-Methylheptyloxycarbonyl] phenyl-4�f-Octyloxybiphenyl-4-carboxylate) molecule, which is applied to liquid crystal display, in gaseous and crystalline phase. In Section 5, we have performed molecular dynamics simulations for the crystals of synthetic sugar-based bolaamphiphiles with two D-galactosyl-or D-glucosylamine rings to understand the origin of a bend structure of 1-galactosamino bolaamphiphile (Gal-10-Gal) in a crystalline phase. In Section 6, we describe a new accelerated molecular dynamics method combined with the multiple time step integration method and fast multipole expansion method for the NTP ensemble system.