Million-atom molecular dynamics simulation by order-N electronic structure theory and parallel computation

Parallelism of tight-binding molecular dynamics simulations is presented by means of the order-N electronic structure theory with the Wannier states, recently developed [J. Phys. Soc. Jpn. 69 (2000) 3773]. An application is tested for silicon nanocrystals of more than millions atoms with the transferable tight-binding Hamiltonian. The efficiency of parallelism is perfect, 98.8%, and the method is the most suitable to parallel computation. The elapse time for a system of 2 x 106 atoms is 3.0 min by a computer system of 64 processors of SGI Origin 3800. The calculated results are in good agreement with the results of the exact diagonalization, with an error of 2% for the lattice constant and errors less than 10% for elastic constants.