Development of Theoretical Calculation System for Computationally Demanding Molecules with High Cost-Performance

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The purpose of this project is to construct a computer system which is cheap but runs fast with parallel computing technique and to investigate chemical reactions of molecules consisting of 30-50 atoms.Alpha CPUs of Digital Equipment Corporation were used in order to construct a workstation cluster. Gaussian and GAMESS were employed as a main program code for theoretical calculations, since these have many users in the world. The interface of parallel computing is conventional TCGMSG and popular MPI (PVM) codes.In 1997, the preliminary code was developed using PVM ; PVM is quite similar to MPI and it is easy to translate PVM language into MPI, The test results of Gaussian 94 with PVM can be found in the web site of Scientists' Paradise Inc. In 1998, MPI version of Gaussian 94(98) has been developed for Alpha-CPU cluster and NEC supercomputer SX-5 with help of NEC Corporation. However, we have a problem of copy-right for Gaussian, so that MPI version of Gaussian cannot be opened to publ … More ic. The test results are presented in the web site of Scientists' Paradise Inc.On the other hand, GAMESS has been parallelized using an interface of TCGMSG.In 1997, this version was introduced into our computer cluster system. The test results can be found in Koseki's web site. Unfortunately, TCGMSG becomes traditional, and the office of GAMESS has started developing MPI version of GAMESS.In order to avoid wasting time, we obtained and modified the official MPI version of GAMESS and ran on our Alpha-CPU cluster machine, The test results, shown in the web site of Scientists' Paradise Inc., are quite attractive.Using the developed system, we started studying on chemical reactions of relatively larger molecules (more than 30 atoms). 4-CPU cluster is about 3 times faster than 1-CPU workstation, and 8-CPU cluster is 6-7 times as fast as I-CPU system. This system very much helps our theoretical investigation of chemical reactions. Especially, it is useful that post Hartree-Fock calculations, such as MCSCF + MP2 calculations, can be carried out rather easily and quickly. Less