OPAL: A New Multiscale Software Architecture Based on MPI-2

Software integration for multi-scale simulations is a time-consuming process. Common practice is to turn the higher level calculation code ( e.g. DFT ) into a subroutine of the lower level calculation code ( e.g. MD ). This method often requires non-trivial effort. To avoid these difficulties, we have developed a software package OPAL, within which a minimal development effort is required to build a working multi-scale environment. We report our effort of integrating DL\_POLY and SIESTA codes for hybrid quantum-classical simulations. This work is supported the NSF through ITR-medium (NSF/DMR/ITR-0218957) program. The authors want to thank NERSC, CNMS/ORNL and the University of Florida High Performance Computing Center for providing computational resources and support that have contributed to the research results reported within this paper.