NANOPACK: PARALLEL CODES FOR SEMIEMPIRICAL QUANTUM-CHEMICAL CALCULATIONS OF LARGE SYSTEMS IN THE SP- AND SPD-BASIS

Abstract

A parallel implementation of the conventionally used NDDO (MNDO, AM1, PM3, CLUSTER-Z1) and modified NDDO-WF (CLUSTER-Z2) techniques for semiempirical quantumchemical calculations of large molecular systems in the sp- and spd-basis, respectively, is described. The atom-pair distribution of data over processors forms the basis of the parallelization. The technological aspects of designing scalable parallel calculations on supercomputers (by using ScaLAPACK and MPI libraries) are discussed. The scaling of individual algorithms and entire package was carried out for model systems with 894, 1920, and 2014 atomic orbitals. The package speedup provided by different multi-processor systems involving a cluster of the Intel PIII processors, Alpha-21264- processor-built machine MBC-1000M, and CRAY-T3E, is analyzed. The effect of computer characteristics on the package performance is discussed.