Effect of defects, dislocations, and grain boundaries on phase transitions by means of molecular simulation methods

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[1] The molecular simulation codes, MXDORTO, MXDTRICL, and MCORTO, were enhanced. The revision were made mainly 1) formalism of (NPT) ensemble algolithm, and 2) the application to structural phase transitions, using the equation of motion of elastic body. The new model of interatomic potential also developed and adopted.[2] The interatomic potential model for H2O, CaO, and CaTiOS in 2000, and for NH3, GaN and other complex systems in 2001 were developed and refined.[3] The intial structure generator for point defects, dislocations, and interface between crystalline grains are developed for molecular simulations. The generated structures are used for estimating relative stability between structures, structural transformations, energy of defects and dislocations, and so on.[4] The distributed parallel computing system was constructed for large scale molecular simulations. The system includes 4 dual-CPU computers (8 cpu's) and the efficient computer codes were developed for molecular simulations and the analyzes ;[5] The/initial structures with various directions of dislocations of GaN (wurtzite structure, hexagonal) were prepared, and the relative stability and structural and energitic dynamics were investigated.