From moshe_o@VNET.IBM.COM Sun Nov 26 08:53:02 1995 Received: from VNET.IBM.COM for moshe_o@VNET.IBM.COM by www.ccl.net (8.6.10/950822.1) id IAA15446; Sun, 26 Nov 1995 08:38:39 -0500 Message-Id: <199511261338.IAA15446@www.ccl.net> Received: from HAIFASC3 by VNET.IBM.COM (IBM VM SMTP V2R3) with BSMTP id 2595; Sun, 26 Nov 95 08:38:32 EST Date: Sun, 26 Nov 95 14:45:00 IST From: "Moshe Olshansky" To: chemistry@www.ccl.net Subject: Combining different basis sets - a summary Dear netters! About 10 days ago I asked the following question: > Dear CCL'ers! > We are working on computational aspects of the Hartree-Fock procedure. > For this purpose we would like to have some f-type basis functions > but not too many of them, while all the basis sets we have either > do not have f functions at all or have too many of them (our trial > molecule contains H C N and O atoms). > Since we are not chemists I would like to ask the following > (possibly very trivial) question: does it make any sense to combine > two different basis sets (for example, take a smaller basis set for > H and C and a larger one - containing d and f functions - for N and O)? First of all, I wish to thank all those who replied to this questions. Basically I got two kinds of responses: some stress the dangers of doing so (talking about Basis Set Superposition Error, etc.), while others say it can (and is being) done, though some caution is needed. Below are the responses I got. Moshe Olshansky IBM Israel Science and Technology ========================================================================= Date: Tue, 14 Nov 1995 17:46:52 +0100 From: aiba@ir.phys.chem.ethz.ch (Ayaz Bakasov, Phys. Chem., ETH Zurich) To: moshe_o@vnet.ibm.com Subject: Re: CCL:Combining different basis sets Dear Mosche, that naive idea of combining (straightforwardly) arbitrary basis sets is not so harmless as it could seem at first glance. The dangers have been recognized long ago, and have been discussed, for instance, in chapter 18 "Balancing basis sets" (page 333) of the following review: Sigeru HIZINAGA "Basis sets for molecular evaluations" Computer Physics Reports 2 (1985) 279-340. The error caused by an unbalanced basis set is normally called "basis set superposition error". The best, Ayaz Bakasov. P.S. Na pal'tsakh: slishkom bol'shoi basis na kakom-libo atome "otsasyvaet" neproportsional'no bol'shoi ob'em volnovoi funktsii na etot atom. ========================================================================= Date: Tue, 14 Nov 95 12:21:32 EST From: "Janet Del Bene" Subject: Your question - Moshe, You did not state specifically the problem of interest, but I am sure that you are aware that there is a basis-set dependence of computed results. To arbitrarily put a larger basis set on some atoms and smaller sets on others would bias your results. Hope this helps. Janet E. Del Bene ========================================================================= Date: Tue, 14 Nov 1995 18:52:45 +0100 From: mas@qc.ag-berlin.mpg.de (Marek Sierka) Message-Id: <9511141752.AA18630@gea.qc.ag-berlin.mpg.de> Subject: Basis Set Dear Moshe, Good basis set has to be properly balanced, otherwise it introduces so called Basis Set Superposition Error. In case of the unbalanced basis set, it leads to the artificial charge transfer, and also gives nonphysical, stabilizing contributions to the enery of molecule. This stabilizing will then occure irrespective of whether there is any genuine binding interaction in the molecule or not. It will give a spurious increase in the binding energy.The choice of proper basis set is kind of art, so you have to be very careful about it. Try this: http://www.emsl.pnl.gov:2080/forms/basisform.html This www server contains several basis sets, so maybe you can find something useful. Marek Sierka Max-Planck Society Quantum Chemistry Group at the Humboldt Univ. Joegerstrasse 10/11 D-10117 Berlin, Germany e-mail: mas@gea.qc.ag-berlin.mpg.de ========================================================================= Date: Tue, 14 Nov 1995 13:23:54 -0500 From: "E. Lewars" Subject: COMBINING BASIS SETS Hello, Yes, you can combine basis sets. For example, the 3-21G* basis has d orbotals on atoms beyond Ne, bot no d's on H--Ne. Some people would call it an "untempered" or uneven basis set, but it works well (see *Practical Strategies for Electron Structure Calculations*, by Warren Hehre, 1995). Also, in papers in on oxirenes, I think Schaefer and coworkers used f and maybe g functions on some atoms but not other: J Phys Chem 98 (1994) 8660 J Am Chem Soc 116 (19940 9311 j aM cHEM sOC 116 (1994) 10159 oF COURSE, THE WIDELY-USED 6-31g* basis has d functions on He, Li, Be, etc, but not on H, and 6-31G** has p's on H but d's on He, Li, etc. Errol Lewars ========================================================================= From: David Heisterberg Date: Tue, 14 Nov 1995 13:35:35 -0500 Subject: Re: CCL:Combining different basis sets There is a school of thought that says that basis sets should be similar for each atom, or at least similar for all important atoms, such as those involved in bond breaking/making. This is especially important if you are interested in any basis-set dependent information, such as partial charges. But it might also be important for a purely computational study -- during the SCF, an "unbalanced" basis-set might exhibit changes in the density matrix that are really just artifacts, and wouldn't appear as significant changes in the Fock matrix. I would suggest looking at the basis sets available from PNL, especially the so-called correlation consistent (cc) sets. The cc-pVTZ set for C, N, and O are of the form (4S,3P,2D,1F). They are web-accessible at http://www.emsl.pnl.gov:2080/forms/basisform.html Dave Heisterberg ========================================================================= From: Jiri Czernek Subject: Re: CCL:Combining different basis sets Date: Tue, 14 Nov 1995 20:30:42 +0100 (MET) Hi again ! :-) I think you risc the basis set for your molecule will be ILL-BALANCED. For explanation I'll cite from some book by Huzinaga: "If basis sets of different quality are placed on atomic sites of a molecular system, the calculated electron distribution may show artificial distortion. Improperly balanced basis sets may yield results even worse than basis sets of uniformly poorer quality." Hope this helps :-) Cordially , George ========================================================================= From: bschmitz@chm.uri.edu Date: Tue, 14 Nov 1995 17:28:00 EST Subject: basis sets Hi Dr. Olshansky, You are apt to get two very different responses to this question. From a purist's point of view differeent basis sets probably shouldn't be combined but from a practical point of view its often necessary. I'm assuming by d and f type functions you mean d and f type gaussians. These are frequently treated as "polarization" functions and are often added to some atoms in a molecule but not others. They are almost always necessary to accurately model the behavior of nitrogen and oxygen atoms. Because we have such a small computer here at URI we often have to combine basis sets. To toot my own horn: A Comparitive Theoretical Study of Hydrazine", Brian K. Schmitz and William B. Euler, Journal of Molecular Structure(Theochem), 257, 1992, 227. Here are some other references I have to hand: Binkley, J. S.; Pople, J.A.; Hehre, W.; Self-Consistent Molecular Orbital Methods. XII. Further Extensions of Gaussian Type Basis Sets for Use in Molecular Orbital Studies of Organic Molecules, Journal of the American Chemical Society, 1980, 102, 939. Boys, S. F.; Electronic-Wave Functions I. A General Method of Calculation for the Stationary States of Any Molecular System, Proceedings of the Royal Society (London), 1950, A200, 542. Defrees, D. J.; Raghavachari, K.; Schlegel, H. B.; Pople, J.A.; Effect of Electron Correlation on Theoretical Equilibrium Geometries. 2. Comparison of Third-Order Perturbation and Configuration Interaction Results with Experiment, Journal of the American Chemical Society, 1982, 104, 5576. Ditchfield, R.; Hehre, W.J.; Pople, J.A.; Self-Consistent Molecular-Orbital Method.IX. An Extended Gaussian-Type Basis for Molecular Orbital Studies of Organic Molecules, Journal of Chemical Physics, 1971, 54, 724. Dunning, T. H.; Gaussian Basis Functions for Use In Molecular Calculations. I. Contraction of Atomic Basis Sets for First Row Atoms, Journal of Chemical Physics, 1970, 53, 2823. Hariharan, P. C.; Pople, J. A.; The influence of polarization Functions on Molecular Orbital hydrogenation Energies, Theoretica Chimica Acta, 1973, 28, 213. Hinchliffe, A.; Ab Initio Determination of Molecular Properties, IOP Pub., ltd., England , 1987, 9. Huzinaga, S.; Gaussian-Type Functions for Polyatomic Systems.I., Journal of Chemical Physics, 1965, 2, 1293. Jensen, J. H.; Gordon, M. S.; Splicing I. Using Mixed Basis Sets in ab initio Calculations, Journal of Computational Chemistry, 1991, 12, 421. Klopper, W.; Kutzelnigg, W.; Gaussian Basis Sets and the Nuclear Cusp Problem, Jorunal of Molecular Structure(Theochem), 1986, 28, 339. Krishnan, R.; Binkley, J.S.; Seeger, R.; Pople, J.A.; Self-consistent Molecular Orbital Methods. XX. A Basis Set for Correlated Functions, Journal of Chemical Physics, 1980, 72, 650. Ohta, K.; Nahatsuji, H.; Hirao, K.; Yonezawa, T.; Ab initio Calculation of Hyperfine Splitting Constants of Molecules, Journal of Chemical Physics, 1980, 73, 1770. Poirier, R.; Kari, R.; Csizmadia, I. G.; Handbook of Gaussian Basis Sets, 1985, Elsevier, New York, Appendix F. Pulay, P.; Fogarasi, G.; Pang, F.; Boggs, J. E.; Molecular Geometries, Force Constants, and Dipole Moment Derivatives, Journal of the American Chemical Society, 1979, 101, 2550. Pulay, P.; Fogarsi, G.; Pongor, G.; Boggs, J.; Varga, A.; Journal of the American Chemical Society, 1983, 105, 7037. Riggs, N. V.; Radom, L.; The 3-21G(N*) Basis Set: An Economical Polarized Basis set for ab initio Studies on Nitrogen Containing Molecules, International Journal of Quantum Chemistry, 1987, 31, 93. Riggs, N. V.; Radom, L.; An ab initio Investigation of the Equilibrium Structures of Hydrazine and the Transition Structures Connecting Them, Australian Journal of Chemistry, 1986, 39, 1917. Shavitt, I.; Methods in Computational Physics, Vol. 2, eds. Alder, B.; Fernbach, S.; Rothenburg, M; Academic Press, New York, NY, 1963, 3. Yours truly, Brian Schmitz e-mail: BSchmitz@chm.uri.edu ========================================================================= Date: Tue, 14 Nov 95 19:02:39 -0330 From: cory@bohr.chem.mun.ca (Cory C. Pye) Subject: Basis sets For molecules containing only H, C, N, and O atoms, for a Hartree-Fock calculation you probably don't need d or f-functions for C, since C is (usually) in a fairly symmetric environment (especially sp3 carbons). They might come in handy for an sp2 or sp carbon to help describe the pi-bonds. Oxygen and Nitrogen should definitely have d-functions, and in some of my work on BSSE (C. C. Pye, R. A. Poirier, D. Yu and P. R. Surjan, {\em J. Mol. Struct. (Theochem)}, {\bf 307} (1994) 239 ), they were somewhat important for Nitrogen (f-functions, that is). I think as long as the occupied s & p functions are consistent for different atoms, you probably won't have to worry about unbalanced basis sets too much. So from best to worst: C df, N df, O df H p C d , N df, O df H p C d , N df, O d H p C d , N d , O d H p C d , N d , O d N d , O d (probably) Hope this helps a bit. -Cory ************* ***************** ! Cory C. Pye *** ** ** ** ! Graduate Student ** * **** ! Unpaid Sys Admin ** * * ! Theoretical and ** * * ! Computational Chemistry *** * * ** ! ***************** ! Les Hartree-Focks ************* ! (Apologies to Montreal Canadien Fans) ========================================================================= From: Christopher J Cramer Subject: Re: CCL:Combining different basis sets Date: Tue, 14 Nov 1995 17:06:51 -0600 (CST) Moshe, > > We are working on computational aspects of the Hartree-Fock procedure. > For this purpose we would like to have some f-type basis functions > but not too many of them, while all the basis sets we have either > do not have f functions at all or have too many of them (our trial > molecule contains H C N and O atoms). > Since we are not chemists I would like to ask the following > (possibly very trivial) question: does it make any sense to combine > two different basis sets (for example, take a smaller basis set for > H and C and a larger one - containing d and f functions - for N and O)? > Particularly with respect to polarization functions, I believe that you are correct in your assumption that they may be more important on some atoms than on others. This is in fact widely accepted (if not necessarily consciously) when one refers to atoms from different rows (e.g., 6-31G* puts polarization functions on C but not H, 3-21G(*) puts polarization functions on P but not C, etc.) It is much less common to discriminate between atoms within the same row. However, we ourselves have recently optimized a variation of the MIDI basis set (we call it MIDI! "midi-bang") with the goal of developing a small basis set that gives high quality geometries and atomic partial charges from HF calculations. In that process, we discovered that d functions on C were unimportant even though they were critical for N and O (this for a test set spanning a wide range of organic functionalities). Of course, we are interested in properties other than the total energy, where we have not tested the utility of the basis set (mind you, it will probably perform no more poorly than any other small basis set). So, with some judicious comparisons made first, I would say that you can legitimately tailor your polarization space to suit your needs without fear of catastrophic consequences. Chris -- Christopher J. Cramer University of Minnesota Department of Chemistry 207 Pleasant St. SE Minneapolis, MN 55455-0431 -------------------------- Phone: (612) 624-0859 || FAX: (612) 626-7541 cramer@maroon.tc.umn.edu http://dionysus.chem.umn.edu/ ========================================================================= From: Marcelo Giordan Santos Subject: Combinning Different Basis Sets. Date: Wed, 15 Nov 1995 12:34:21 -0200 (EDT) Dear Mosche, There are many examples in the literature, that combine different kinds of basis sets, even among the same element. In my opinion there is no problem in mixing different basis sets of different degree of quality for the same molecule. But, you should examine your results in the light of this apporach. I've an article about pyrrolizidine alkaloids in which i mix different kinds of basis sets, utilizing pseudopotential and all-electrons approach. It will appear in the fortcomming numbers of J. Comp. Chem. Best regards, Marcelo Giordan. -- &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& & Marcelo Giordan & EDM - Faculdade de Educacao - USP & Av. da Universidade 309, & Cid. Universitaria, Sao Paulo, S.P. & CEP: 05508-900 , Brazil & & ##################################### & e-mail: giordan@usp.br & voice: 55-11-8150297 & fax: 55-11-8183149 & & &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& From rull@rhino.chem.ruu.nl Fri Nov 24 11:53:16 1995 Received: from chemail.chem.ruu.nl for rull@rhino.chem.ruu.nl by www.ccl.net (8.6.10/950822.1) id LAA21395; Fri, 24 Nov 1995 11:53:13 -0500 Received: from rhino (rhino.chem.ruu.nl) by chemail.chem.ruu.nl with SMTP id AA27075 (5.67b/IDA-1.5 for <@chemail.chem.ruu.nl:chemistry@www.ccl.net>); Fri, 24 Nov 1995 17:54:20 +0100 Received: by rhino (931110.SGI/930416.SGI.AUTO) for @chemail.chem.ruu.nl:chemistry@www.ccl.net id AA18741; Fri, 24 Nov 95 17:53:33 GMT From: "Ton Rullmann" Message-Id: <9511241753.ZM18739@rhino.chem.ruu.nl> Date: Fri, 24 Nov 1995 17:53:28 +0000 Reply-To: rull@ruuci9.chem.ruu.nl To: chemistry@www.ccl.net Subject: MachTen (Unix for Mac) - summary A few weeks ago I asked for info about MachTen, an implementation of Unix for Macintosh. A summary of the replies - all favourable - is included below. I also learned that an article about MachTen (focusing on its use as Internet Server) appeared in MacUser of March, 1995. Since one or two people asked about X-window implementations for Mac, I try to summarize a few things that have been sent on the ccl. * MachTen supports X11R5. In some versions you have to buy the X-window software separately (see info available from Tenon Intersystems, 1123 Chapala St. Suite 202, Santa Barbara, CA, 93101 (805) 963-6983, (805) 962-8202 fax sales@tenon.com, http://www.tenon.com/ ) * Linux might be an alternative, when a port to Mac (apparently under way) is ready. * MacX is mentioned several times. This is an Apple product. I have seen it in action, and was happily surprised by the speed on a Power Mac 8100. It has iconizable windows that are displayed on the Mac desktop (in "rootless mode"), and all settings and documents can be saved in startup documents. * An (incomplete??) mail recently sent by Raymond C. Fort, Jr. (rcfort@maine.maine.edu) on the ccl mentions a product called Xoftware, but I have no idea what it is. Thanks to everybody who replied, and sorry for the delay in summarizing. Ton Rullmann. *********************************************************************** We are also trying to obtain information regarding MachTen. Unfortuneately we have been playing "phone-tag" with the technical staff at Tenon. If and when we learn more we will communicate that to you. Please send us your summary of responses. Thanks, Carol Carol Parish Ph.D. Department of Chemistry carol@still3.chem.columbia.edu Columbia University (212) 854-5143 New York, NY 10027 (718) 981-0356 *********************************************************************** Heb er al het een en het ander van gehoord (meestal vrij positief). Hou je mij op de hoogte van de antwoorden (kan ik op mijn Power Mac thuis ook Unix draaien :-) P.S. Er is een port naar de Power Mac bezig van Linux. [my translation: Have heard some things about it, mostly reasonably positive. Keep me posted, so I can run Unix at my PowerMac at home :-) PS. Linux is being ported to Power Mac.] Kris Boulez (Kris.Boulez@rug.ac.be) Biomolecular NMR unit University of Ghent, Belgium *********************************************************************** I'm very satisfied. In fact, the existance of Machten influenced my decision to purchace a Mac (PowerPC 7100/80) over a Pentium based PC. (especially since I really hated the idea of using MicroSerf Dog and MicroSerf Windoze!) The latest PPC release (4.0) is really nice (even though it doesn't use virtual memory...) and comes with native X11R5. A few caveats if you're doing code development the g77 compiler is buggy, but that's a problem with g77 and not Machten. Since g77 is basically an interpreter for gcc, I'm not too surprized...besides it's still a "beta" release. The c-compiler (gcc) is pretty nice, although here are some pecularities that folks have reported. Fortunately, there's a pretty active e-mail list which can very useful in finding folks who have solved whaat ever new problem you discover. Plus the MachTen support staff is really top-notch. As far as speed. MachTen runs as a application and interacts fully with the MacOS...So, you get the full benefits of the PPC chip. Also, you can adjust the scheduling preferences (Mac vs. Unix) using the control panel...so if you're running code, crank up the Unix or turn it down when using Mac applications. I usually keep things set at about 60:40 Mac:Unix since I mainly use MT for TCP/IP, mail, and httpd services. When I get some time, I plan to compare its number crunching capabilities with some other computers we have around. For a UnixOS...it is as good as anything I've used, and in many ways easier to administer. Installation is a no-brainer. The CD-rom comes with with everything ready to go. Compatability. Again, it's just like using unix on a Sun station...only you have all the features of a Mac as a plus. There are some quirks and system hang-ups every once in a while, but I'm nott totally convinced MT is to blame. System requirements: I have 49Mbytes RAM which I find to be OK as along as I don't have a lot of other applications. (24 Mbytes is builtin and the remainder is virual) Right now, (running just the Finder and MachTen with about 10 mac windows open) the finder is using 8Mbytes and MT 4Mbytes...Cranking up X11 will boost the memory used by the *finder* up to about 10 or 11 Mbytes and each new x-window or application will eat up about .75 Mbytes. Emacs is a real memory hog (no as bad as MSWord)...but MachTen comes with BBEdit, which is very nice as a small memory footprint editor. There are some tricks one has to play in order to move Mac files and Unix files, especially if you're like me and have a laser printer hooked up to remote unix machine. The problem is that Mac files have both resource and data forks where as unix uses only data forks. Of course the folks at Tenon have realized this and provide useful filters for converting back and forth. Unlike linux, you can switch baack aand forth between unix and mac by just clicking. You can move Mac files into the unix folder and vice versa. Using links, you can mount Mac folders in the unix folder. External disks (Zip disks, floppies, and CDs) are mounted automatically in a unix volume so that you can "cd" right on to the disk. Eric Dr. Eric R. Bittner phone: (512)-471-1092 Dept. of Chemistry and Biochemistry fax: (512)-471-16224 Univ. of Texas at Austin email: bittner@eiger.cm.utexas.edu http://eiger.cm.utexas.edu *********************************************************************** I use it, and overall, I like it. The X/Windows implmentation is certainly better than Mac/X and (I think) at least as good as eXceed or eXodus. MacTen is based on the Mach kernel (of course), and it shows in places: MachTen claims to be 4.3BSD, but it's not *really*. Most things can be compiled with a bit of work; some things cannot without a LOT of work. Some things, like mmap() are hopelessly broken. This is all regarding the 68k version, btw (MachTen 2.2). I haven't tried the PowerMac version, but from what I understand, It would be best to wait for the second (or third...) release, as some vital features (virtual memory, linking against Xlib) aren't there yet! Ernest Friedman-Hill Phone: (510) 294-2154 Scientific Computing FAX: (510) 294-2234 Sandia National Labs ejfried@ca.sandia.gov Org. 8117, MS 9214 http://herzberg.ca.sandia.gov PO Box 969 Livermore, CA 94550 *********************************************************************** Date: Tue, 31 Oct 1995 15:50:22 -0500 From: rcfort@maine.maine.edu (Raymond C. Fort, Jr.) Subject: CCL:Summary of X-clients [...stuff deleted...] MacX was the only software mentioned for Macintoshes, with positive experiences reported by Stephen Bowlus (BOWLUS@sandoz.com), Per Arvidsson (arvid@oc.chalmers.se), Dave Young (young@slater.cem.msu.edu), and Craig Burkhart (cburkhart@goodyear.com). We have some small experience with MacX ourselves, and find it usable, although a bit clunky. [...stuff deleted...] *********************************************************************** Date: Wed, 1 Nov 1995 09:56:27 -0500 Logic, Inc. (sales@age.com). Katie Breen was particularly helpful in faxing me a copy of the sales brochure. Xoftware comes in versions for both PC and Mac; Craig Martens (cmartens@uci.edu) has a positive experience with the Mac version. We will order trial [...stuff deleted...] Professor Ray Fort, Jr. Voice: (207)-581-1180 Department of Chemistry FAX: (207)-581-1191 University of Maine E-mail: rcfort@maine.maine.edu Orono ME 04469 rfortjr@fort.umeche.maine.edu *********************************************************************** Date: Sat, 15 Oct 1994 08:43:52 -0500 (EST) From: Phil Bays Subject: CCL:X windows on the Power PC We use all our MacIntoshes as X displays for Felix successfully, using the software MaxX. A couple of years ago I believe MacX sold for about $200. All of our Macs and SGIs are of course connected over an ethernet, thus MacX allows us also to use the Mac as an X terminal for workstations. The trickiest part about getting Felix to display thru MacX is getting the settings in the MacX setup correct. Once you have installed MacX on your MacIntosh, start it up, and under Remote choose Edit Command. The command line you enter must be: /usr/bin/X11/xterm -ls -title "@host xterm" -sb -display "@display" where I've used the @ symbol here in place of the R-in-a-circle symbol (the trademark symbol---I don't remember how to make it on the Mac). Then, Command Name can just be the user's login name for the SGI. Display MUST be (2)Color Rootless Output Save For Host, add your SGI's hostname to the list and choose it. For Method, we use MacTCP Tool, already installed on our Mac. This works well for us. I know that there are variations of the command line above that starts with /usr/bin...... becasue once I had to work with a Mac expert to get it to work on someone else's Mac, and I know we ended up with soemthing slightly different from above. Also that particular time we kept running into out-of-memory errors from the Mac, and all she then did was increase the Mac's virtual memory and everything was fine. There is a more complete writeup of how to do this in my old Biosym notebook from when I was still at Biosym, so if you have a Customer Support contract with Biosym, simply send them email at rcenter@biosym.com and request the instructions for doing this--the person in the Felix support job now will know what to send you. Kelly Keating Dept. of Chemistry Emory University Atlanta, GA 30322 *********************************************************************** -- J.A.C. Rullmann http://www-nmr.chem.ruu.nl/users/rull/rull.html Bijvoet Center for Biomolecular Research E-mail : rull@nmr.chem.ruu.nl Utrecht University, Padualaan 8, Phone : int+31.30.2533641 3584 CH Utrecht, the Netherlands Fax : int+31.30.2537623 ^ NOTE: phone numbers have changed - insert a 2 From CTARG@Levels.UniSA.Edu.Au Sun Nov 26 17:53:10 1995 Received: from CAM.Levels.UniSA.Edu.Au for CTARG@Levels.UniSA.Edu.Au by www.ccl.net (8.6.10/950822.1) id RAA20519; Sun, 26 Nov 1995 17:51:17 -0500 From: Received: from Levels.UniSA.Edu.Au by Levels.UniSA.Edu.Au (PMDF V5.0-4 #9510) id <01HY4SIJW79C9AMNOI@Levels.UniSA.Edu.Au> for chemistry@www.ccl.net; Mon, 27 Nov 1995 09:20:53 +0930 Date: Mon, 27 Nov 1995 09:20:53 +0930 Subject: molecular modelling software/hardware To: chemistry@www.ccl.net Message-id: <01HY4SIJYVPE9AMNOI@Levels.UniSA.Edu.Au> X-VMS-To: IN%"chemistry@www.ccl.net" MIME-version: 1.0 Content-type: TEXT/PLAIN; CHARSET=US-ASCII Content-transfer-encoding: 7BIT Hi, I have a problem with software/hardware compatability. Next year I would like to upgrade my workstation - I'm looking at a Dec Alpha of a Sun Ultra. The problem arises with compatible software. I need something that is networkable, up to four users at a time and can do force field, semi-empirical and (hopefully) ab-inito molecular modelling. This software is also required to be cheap! I can't afford to pay huge somes of money. Does anybody know of any software that can do one (or all) of these things? I would very much appreciate hearing from people who have set up similar (cheap) systems. Thanks very much Andrea