Atomistic Computer Simulation Studies on the Grain Boundary Properties of Nickel-Aluminide and Silicon

抄録

Using the computer simulation technique based on the LCAO (linear combination of atomic orbitals) electronic theory, we study the grain boundary properties of the metal systems (Ni₃Al crystal with L1₂ structure) as well as of covalent semiconductor (Si) crystals. Specifically, we calculate the atomic configuration, segregation energy of solute atoms and cleavage strength of the symmetrical tilt grain boundaries. We assume that the total energy of the system is given by a sum of the band structure energy and the pairwise repulsive potential energy. For the calculation of band structure energy, we use the recursion method of s, p and d-basis orbitals and local charge neutrality condition. For the repulsive potential energies, specific spatial dependence is derived by either Poudolocky-Pettifor formulation (for the intermetallic compound) or the extended Hiückel theory (for the covalent semiconductor), depending on the nature of atomic bonding of the material. We will show that the present analysis of the LCAO scheme is quite useful and suggestive for the interpretation of various experimental results on grain boundary properties of metal systems and of covalent semiconductor crystals.