DIRECT-SEARCHER SYSTEM (Ver. 3) FOR SOME ORGANIC COMPOUND ON PERSONAL COMPUTERS. K. Okada^1*) and S. Okada^2), 1)Research & Development Center, Ricoh Co. Ltd., Tsuzuki-ku, Yokohama 224, Japan, 2)Faculty of Engineering, Science University of Tokyo, Shinjuku-ku, Tokyo 161, Japan.

The Direct-Searcher system version 3 (DS*System3) has been developed for automatic structure analysis of some organic compounds running on personal computers (PC). The DS*System3 running on Windows NT is the latest version developed for Cray-1 / CDC6600 (Ver.1, J.Chem.Soc.B,1969,940; Acta Cryst.1990, A46, C70) and mainframe / workstation / PC (Ver.2, Comput.Chem.1995, in press). An organic chemist as well as a crystallographer can get results very easily with his own well-known PC. This system consists of more than twenty crystallographic programs, and each program is improved and re-written in the Fortran language. The logical structure of DS*System3is simplified as three layers by using common and independent libraries for easy maintenance. The major improvements are: Loose limitation of no. of atoms, reflection and equiv.position; Color display; Plotter output; Change peak find algorithm; Adoptd at a base for space group and atomic scattering factor; add CIF facility; bag fixing. We found that the molecular skeleton takes usually less than 2 min with heavy-atom analysis (PSL3+Searcher3) and 15 min with direct methods (Dircter3) by a Pentium 100PC. Comparing the computational speed, the PC has a capability of 1.55 times a Cray-1, 3.93 times a HP9000/755,7.43 times a IBM3090-200E and 33.2 times a CDC6600. The crystal structure analysis of organic compounds has been carried out more than fifty with the heavy-atom analysis and more than thirty with the direct methods.