Top Document: Sci.chem FAQ - Part 5 of 7 Previous Document: 20. Optical properties of chemicals Next Document: 22. Spectroscopic Techniques See reader questions & answers on this topic! - Help others by sharing your knowledge Supplied by: Dave Young (young@slater.cem.msu.edu) 21.1 What hardware do I need to run modelling programs? There are two types of programs that are referred to as molecular modeling programs. This first is a program which graphically displays molecular structures as Lewis structures, ball & stick, etc. The second is a program which does a calculation to tell you something about the molecule, such as it's energy, dipole moment, spectra, etc. For an introductory description of various types of computations, see http://www.cem.msu.edu/~young/topics/contents.html There are many programs of both sorts available for a large range of machines. The speed, memory, graphics and disk space on the machine will determine the size of molecules that can be modelled, how accurate the model is, and how good the images will look. There are a few programs that will run on a 286 PC with Windows. There are some fairly nice things that can be done on a 386 with about 8 MB of RAM and Windows. The professional computational chemists are generally using work stations and larger machines. Currently many computational chemists are using machines made by Silicon Graphics (SGI) ranging from the $5,000 Indy to the $1,000,000 power challenge machines. These are all running Irix, which is SGI's adaptation of Unix. SGI is popular for two reasons; first that the power is very good for the price, second that SGIs run the largest range of chemical software. However, you will find some computational chemistry software that can run on almost any machine. As far as graphics quality, the SGI Onyx (about $250,000) is about the top of the line. Even if you find a machine that claims to have better graphics than this, chances are you won't find and chemistry software that can utilise it. For chemical calculations there is no limit to the computing power necessary. There are some calculations that can only be done on the biggest Crays or massively-parallel machines in the world. There are also many calculations which are too difficult for any existing machine and will just have to wait a few years or a few centuries. 21.2 Where can I find a free modelling program? The single best place for public domain modelling software is probably the anonymous FTP server at ccl.osc.edu in the directory pub/chemistry/software. "ccl" stands for "computational chemistry list server" and is a list frequented mostly by professional computational chemistry researchers. This machine contains their archives with quite a bit of information as well as software. For work stations and larger, the program GAMESS (General Atomic and Molecular Electronic Structure System) can be obtained as source code from Mike Schmidt at mike@si.fi.ameslab.gov GAMESS is a quantum mechanics, ab initio and semi-empirical program. It is powerful. but not trivial to learn how to use. The COLUMBUS program for work stations and larger can be obtained by anonymous FTP from ftp.itc.univie.ac.at It is a HF, MCSCF and multi-reference CI program. This is probably the most difficult program to use that is in use today since it requires the user to input EVERY detail manually. However, because you control everything there are some calculations that can only be done with COLUMBUS. CACAO is an extended Huckel program available by anonymous FTP at cacao.issecc.fi.cnr.it 21.3 Where can I find structural databanks? 21.4 Where can I find ChemDraw or ChemWindows For ChemDraw (Macintosh, Windows, UNIX) CambridgeSoft Corporation 875 Massachusetts Avenue Cambridge, MA 02139 Phone: (800) 315-7300 or (617) 491-2200 Fax: (617) 491-7203 Internet: info@camsci.com http://www.camsci.com For ChemIntosh or ChemWindows SoftShell 1600 Ute Avenue Grand Junction, CO 81501 Phone: (970) 242-7502 Fax: (970) 242-6469 Internet: info@softshell.com http://www.softshell.com User Contributions:Top Document: Sci.chem FAQ - Part 5 of 7 Previous Document: 20. Optical properties of chemicals Next Document: 22. Spectroscopic Techniques Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: B.Hamilton@irl.cri.nz
Last Update March 27 2014 @ 02:12 PM
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