A part of the research performed at the Ames Laboratory was conducted for the US-DOE under its contract with Iowa State University, Contract No. DE-AC02-07CH11358. This research was supported in part through computational resources provided by the Kathmandu University Supercomputer Centre, which was established with equipment donated by CERN. We are very grateful to the Supercomputer Center (Kathmandu University) for providing high performance computing facilities during the research work.