From stevens@rainbow.uchicago.edu Mon Jul 18 09:54:34 1994 Received: from midway.uchicago.edu for stevens@rainbow.uchicago.edu by www.ccl.net (8.6.9/930601.1506) id JAA13947; Mon, 18 Jul 1994 09:26:13 -0400 Received: from rainbow.uchicago.edu by midway.uchicago.edu for CHEMISTRY@ccl.net Mon, 18 Jul 94 08:27:12 CDT Received: by rainbow.uchicago.edu (920330.SGI/920502.SGI) for @midway.uchicago.edu:CHEMISTRY@ccl.net id AA00626; Mon, 18 Jul 94 08:41:42 -0500 From: stevens@rainbow.uchicago.edu (Jonathan Stevens) Message-Id: <9407181341.AA00626@rainbow.uchicago.edu> Subject: geometry optimizations To: CHEMISTRY@ccl.net Date: Mon, 18 Jul 1994 08:41:41 -0600 (CDT) X-Mailer: ELM [version 2.4 PL22] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 288 hello, i am interested to know if there is a good text, or review article, explaining and detailing the various techniques of ab initio molecular geometry optimizations. Thank you in advance, Jonathan E. Stevens From herbert.homeier@rchs1.chemie.uni-regensburg.de Mon Jul 18 11:54:26 1994 Received: from comsun.rz.uni-regensburg.de for herbert.homeier@rchs1.chemie.uni-regensburg.de by www.ccl.net (8.6.9/930601.1506) id LAA18717; Mon, 18 Jul 1994 11:11:37 -0400 Received: from rchs1.chemie.uni-regensburg.de by comsun.rz.uni-regensburg.de with SMTP id AA00946 (5.65c/IDA-1.4.4 for ); Mon, 18 Jul 1994 17:11:31 +0200 Received: by rchs1.chemie.uni-regensburg.de (4.1/URRZ-sub (1.5)) id AA21364; Mon, 18 Jul 94 17:08:28 +0200 Date: Mon, 18 Jul 94 17:08:28 +0200 From: Herbert Homeier (t4720) Message-Id: <9407181508.AA21364@rchs1.chemie.uni-regensburg.de> To: CHEMISTRY@ccl.net Subject: GACS: Summary and some questions Cc: boisvert@cam.nist.gov, yinona@niva.tau.ac.il Hello all, I include the original contribution to CCL and the answers which I received. Many thanks for all contributions. In addition, I contacted also Ron Boisvert who has developed the GAMS system. He offered help (see at the end) and sent me some files/reprints describing the GAMS system. Thank you very much, Ron. I offer to coordinate the GACS project (for some time). Unfortunately, I cannot do all the work myself. Any help is appreciated. I propose to structure the GACS in analogy to the GAMS. Please let me know if a) you want to be on my mailing list for the GACS project and/or b) you would like to contribute to it. Please send copies of further comments and proposals concerning GACS to me. These could include the user interface (which protocols are necessary, which are desirable), the tree structure of problems/subproblems (or alternatives to such a structure), quality control (who should do it, what should be the criteria), already available databases and software archives which should participate (as, for instance, QCPE ; remember: the GACS should be -- like GAMS -- a virtual software repository providing links to places where the software is physically stored. Thus, it is not intended to replace QCPE ...). Now my questions: What is a good estimate for the number of useful (commercial and noncommercial) chemical software moduls which are available now? What do you estimate to be available in five years? If you can give an estimate for a particular field (eg, molecular modeling, ab initio programs, etc) only, I also would like to know. Best regards Herbert -------------------------------------------------------------- Dr. Herbert H. H. Homeier Institut fuer Physikalische und Theoretische Chemie Universitaet Regensburg D-93040 Regensburg, Germany Phone: +49-941-943 4720 FAX : +49-941-943 2305 email: na.hhomeier@na-net.ornl.gov -------------------------------------------------------------- Original Contribution: From herbert.homeier@rchs1.chemie.uni-regensburg.de Fri Jul 8 15:25:14 1994 > To: CHEMISTRY@ccl.net > Subject: GACS (Guide to Available Chemistry Software) Project ? > Reply-To: na.hhomeier@na-net.ornl.gov > Content-Length: 1884 > X-Lines: 55 > Status: RO > > Hello all, > > There a many places where archives for chemistry software > are under current development. But still, software for a > given problem is often difficult to find. > > In my opinion, there is a need for a Guide to Available > Chemistry Software (GACS) Project. It should be similar in > spirit to the Guide to Available Mathematical Software > (GAMS) project. This is a database structured by problem > classes and subclasses. The database contains the pointer to > a place where the software can be obtained. GAMS is available > under gopher or WWW as > # > Type=1 > Name=GAMS (Guide to Available Mathematical Software project) > Path= > Host=gams.nist.gov > Port=70 > URL: http//gams.nist.gov > # > and offers a telnet and an X11 user interface. > > Maybe that some features of a GACS > are already implemented or under construction. > > My question is whether anybody knows of any GACS-like > project or plans for it. If there is some interest group > for such a project, please let me know. > > Perhaps it is not too much effort to get a GACS started. > It might be possible to get interface and database software > from the GAMS people. Then, some people have to decide on a > class/subclass structure of common chemical problems for > which software is available or desirable. The most laborious > part would be to enter the data per software module. But > this could perhaps be done in some "automated" fashion or > by each software provider for his/her software. > > What do you think about this? In case of suffient response > I will summarize to CCL. > > Best regards > > Herbert > > -------------------------------------------------------------- > Dr. Herbert H. H. Homeier > Institut fuer Physikalische und Theoretische Chemie > Universitaet Regensburg > D-93040 Regensburg, Germany > Phone: +49-941-943 4720 FAX : +49-941-943 2305 > email: na.hhomeier@na-net.ornl.gov > -------------------------------------------------------------- > > ANSWERS: -------------------------------------------- > From aiba@volta.vmsmail.ethz.ch Fri Jul 8 18:49:08 1994 > X-Vms-To: ETHZ::"Herbert Homeier (t4720) > " > To: Herbert Homeier (t4720) > Subject: RE: CCL:GACS (Guide to Available Chemistry Software) Project ? > Content-Length: 317 > X-Lines: 16 > > Dear Herbert, > > There is no question that > implementation of such project > would be utterly desirable. > > The possible obstacle is a purely > practical one, in my opinion. > It is who will volunteer to do > hard work and where to get > the resources from. > > I really wish the idea will be implemented. > > Sincerely, > Ayaz Bakasov. > ------------------------------------------- > From 74222.2372@compuserve.com Sat Jul 9 05:36:17 1994 > Resent-From: <74222.2372@compuserve.com> > Resent-Date: Fri, 8 Jul 1994 23:38:54 -0400 > Resent-Message-Id: <199407090338.XAA12344@netlib2.cs.utk.edu> > Resent-To: Herbert.Homeier@chemie.uni-regensburg.de (by na-net.ornl.gov) > To: Herbert Homeier > Subject: Re: GACS proposal > Content-Length: 1466 > X-Lines: 28 > > I very much like the idea of a GACS. The closest existing thing is QCPE, which > is narrower in scope and a lot more restrictive in coverage. However, there are > two potential problems that I wonder how you propose to handle: > > 1. A remarkable number of people (myself included!) do not have access to WWW > (in any practical sense). I have dialup access via CompuServe and Delphi; only > recently have I got 9500 baud access; the channel capacity to handle Mosaic is > just not there. Sure, I can get the Mosaic software for free but I can't > effectively use it. My suggestion: have a "static" copy of the GACS on an FTP > site as a (big!) document; and/or set up a Gopher tree. > > 2. Probably a majority of the software packages for chemistry are commercial, > and as such would not tend to be available directly over the net. How would you > handle indexing commercial software? Let the vendor's marketing department > write the description (at least everything would look *wonderful*! :-) )? > Have independent reviews? By whom? > > The reviews idea sparked a possible suggestion: have an area where satisfied (or > dissatisfied) users of the software could submit comments about their > experience. Does the math package handle this? > > It's a good idea; there is a lot of software - and a lot of wheel-reinvention - > out there. Some accessible central clearing house would be a great idea. > > John Vinson > Wysard of Information > Scientific Information Systems independent consultant > > ------------------------------------------------------- > From yinona@niva.tau.ac.il Sat Jul 9 14:48:22 1994 > Resent-Date: Sat, 9 Jul 1994 08:50:53 -0400 > Resent-From: " Resent-Message-Id: <199407091250.IAA16112@netlib2.cs.utk.edu> > Resent-To: Herbert.Homeier@chemie.uni-regensburg.de (by na-net.ornl.gov) > Subject: Re: CCL:GACS (Guide to Available Chemistry Software) Project ? > To: na.hhomeier@na-net.ornl.gov > Mime-Version: 1.0 > Content-Type> : > TEXT/PLAIN> ; > charset=US-ASCII> > Content-Length: 185 > X-Lines: 8 > > Hi Herbert. > A. let there be GACS soon and we shell all prosper. > B. I would appreciate it if you'll forward any knowledge guthered to me. > cheers > yinon > yinona@niva.tau.ac.il > > > --------------------------------------------- > From Andrepeter.Heiner@vtt.fi Mon Jul 11 08:15:14 1994 > Resent-From: > Resent-Date: Mon, 11 Jul 1994 02:17:57 -0400 > Resent-Message-Id: <199407110617.CAA07417@netlib2.cs.utk.edu> > Resent-To: Herbert.Homeier@chemie.uni-regensburg.de (by na-net.ornl.gov) > To: na.hhomeier@na-net.ornl.gov > Subject: GACS database > Cc: heiner@bel.vtt.fi > Content-Length: 966 > X-Lines: 20 > > > Dear dr. Homeier, > > I think this is a great idea, starting a database of chemical software. However, > to guarantee some level of quality it might be smart to have some refereeing/ > reviewing system as the community is not waiting for a junkyard-type of data > base. > Anyways, I fullheartedly support your initiative > > Andrepeter Heiner > ----------------------------------------------------------------------------- > | A.P. Heiner, Ph.D. | Phone : +358-0-456 5105 | > | VTT | Telefax : +358-0-455 2103 | > | Biotechnology & Food Research | E-mail : andreas.heiner@vtt.fi | > | P.O. Box 1503 | | > | FIN-02044 VTT Espoo | | > | FINLAND | | > ----------------------------------------------------------------------------- > > > ============================================================ My email to Ron Boisvert: Dear Ron, thank you for your answer concerning GAMS covering of symbolic computation software. The crucial problem seems to be man power, then. Unfortunately, I do not have a large group of helpers available, either. The idea with external editors is probably a good one. One could think of using WWW as input facility for descriptions of any contributor which then might be refereed. In this way, one could produce properly formatted database entries easily and combine it with some quality control. (One could think of making available the small (?) database of entries which have not been refereed sofar, on the basis that a label "not refereed" is added to those entries.) I feel that the idea of GAMS is so good that it could well be extended to Guides to Available (...) Software projects, where (...) might be Chemistry, Physics, etc.. I include a message the to the computational chemistry list that points into this direction: (deleted) Now my question raised also above: Would it be possible to obtain software from you to run such a GACS project? How much work would you estimate to develop a GACS with the help of your software, how much without? What are the hardware requirements for a GACS server (amount of disk space, netload) ? Any information will be highly appreciated. Best regards Herbert ======================================== The answer: > From boisvert@cam.nist.gov Fri Jul 8 19:52:32 1994 > Resent-From: > Resent-Date: Fri, 8 Jul 1994 13:55:06 -0400 > Resent-Message-Id: <199407081755.NAA07059@netlib2.cs.utk.edu> > Resent-To: Herbert.Homeier@chemie.uni-regensburg.de (by na-net.ornl.gov) > To: na.hhomeier@na-net.ornl.gov > Subject: Re: A further Question about GAMS > Content-Length: 3022 > X-Lines: 57 > > > I feel that the idea of GAMS is so good that it could well be extended > > to Guides to Available (...) Software projects, where (...) might be > > Chemistry, Physics, etc.. I include a message the to the computational > > chemistry list that points into this direction: > > Thank you very much for your kind words and for recommending GAMS as a > model to your colleagues. > > > Would it be possible to obtain software from you to run such a > > GACS project? How much work would you estimate to develop a GACS > > with the help of your software, how much without? What are the > > hardware requirements for a GACS server (amount of disk space, > > netload) ? > > Yes, you can get the GAMS server and database from us. It is not > commercial grade software, and we modify it continually, so that > someone would have to become an expert in its working in order to > make good use of it. The server is written in C, but the GAMS > database is managed using RIM, a Fortran-based relational database > management system. RIM is sold commercially by various companies, > but we have a public-domain version that runs on a Sun (moving it to > other systems might be a chore -- it requires nonstandard Vax Fortran > extensions which the Sun compiler can handle). We have Fortran > programs that we use to maintain the database (i.e. put in info on > new software, delete things, etc.) There is also a C program that > acts as a gateway between the GAMS server and the WWW. This program > is run by the NCSA HTTPD server software using its Common Gateway > Interface. I will send you serveral papers (as compressed uuencoded > PostScript files) that describe the architecture of the system in a > little more detail. > > gams.nist.gov is a Sun SPARC 10 Model 51 workstation. It has the > native GAMS server, an HTTP server, and a Gopher server. For the > month of June there were a total of about 58000 transactions > processed by these servers. There were 988 GAMS client startups and > 2227 WWW homepage retrievals, whose sum represents the number of > distinct usages of GAMS. Also, this host admits anonymous logins for > gams and xgams users, and there were about 850 of them in June. In > spite of this usage level the system is not particularly taxed. It > could easily handle twice the load it now gets. Since GAMS is a > virtual repository disk space is not a problem for us --- GAMS > indexes external repositories and accesses them on demand on behalf > of users. > > As for development time, having our GAMS system would probably help, > but there would be some initial cost in learning it. The biggest > difficulty would be in designing a usable classification scheme, > classifying the software, and importing this information into the > system. Our database is useful to us since we have a rather large > number of modules (> 9000) in more than 80 packages whose data we > wish to maintain. If the sum total of objects that you are dealing > with is much smaller (on the irder of hundreds), then using GAMS > might be overkill. > > I'd be happy to discuss this further with you. > > - Ron Boisvert > From jeanne@TC.Cornell.EDU Mon Jul 18 13:10:42 1994 Received: from taboo.tc.cornell.edu for jeanne@TC.Cornell.EDU by www.ccl.net (8.6.9/930601.1506) id MAA23461; Mon, 18 Jul 1994 12:30:34 -0400 Received: (from jeanne@localhost) by taboo.tc.cornell.edu (8.6.9/8.6.6) id MAA31232; Mon, 18 Jul 1994 12:18:00 -0400 Date: Mon, 18 Jul 1994 12:18:00 -0400 From: "Jeanne C. Butler" Message-Id: <199407181618.MAA31232@taboo.tc.cornell.edu> To: symp-announce@TC.Cornell.EDU Subject: SYMPOSIUM: Computation in Biophysical Chemistry at Cornell University Cc: cal@TC.Cornell.EDU, donna@TC.Cornell.EDU, jeanne@TC.Cornell.EDU, palmer@TC.Cornell.EDU X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X X-X X-X X-X X-X X-X CORNELL THEORY CENTER SYPMOSIUM X-X X-X COMPUTATION IN BIOPHYSICAL CHEMISTRY X-X X-X OCTOBER 25 - 26, 1994 X-X X-X X-X X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X ABSTRACT: The Cornell Theory Center announces the second in its series of symposia featuring research related to its Parallel Processing Resource for Biomedical Scientists. The Computation in Biophysical Chemistry Symposium will feature an international roster of speakers, and include a poster session and video theatre. WHO WE ARE: The Cornell Theory Center is a national high performance computing and communications resource, as well as an interdisciplinary research center located at Cornell University in Ithaca, NY. The National Institutes of Health awarded funding to the Cornell Theory Center in 1992 to create a resource that applies expertise in parallel computation and algorithm development to biomedical applications. CONFIRMED SPEAKERS INCLUDE: Dr. Jeffrey Skolnick, The Scripps Research Institute Dr. Joel Sussman, Weizmann Institute of Science, Israel & Brookhaven National Laboratory Dr. Guy Montelione, Rutgers University Dr. Harel Weinstein, Mt. Sinai School of Medicine Dr. Harold Scheraga, Cornell University Dr. Arnold Hagler, BioSym Technologies, Inc. Dr. Michael Teter, Corning, Inc. Dr. Ron Elber, University of Illinois at Chicago, and The Hebrew University, Israel Dr. Zhijun Wu, Argonne National Laboratory POSTER SESSION/VIDEO THEATRE: To apply for a poster session and/or video theatre presentation, please send abstract of research to Linda Callahan at cal@tc.cornell.edu by September 23, 1994. HOTEL ACCOMMODATIONS Blocks of rooms have been reserved at the following hotels: Collegetown Motor Lodge 312 College Avenue Ithaca, NY 14850-4624 phone: 607-273-3542 email: reservations@c-town.com rates: $56 - 69 per night Sheraton Inn One Sheraton Drive Triphammer Road and Route 13 Ithaca, NY 14850 phone: 607-257-2000 rate: $65 - 73 per night REGISTRATION: For registration information, send e-mail to donna@tc.cornell.edu or return the form below: Detach here ------------------------------------------------------------------------------- COMPUTATION IN BIOPHYSICAL CHEMISTRY SYMPOSIUM Name: Title: Organization: Address: City/State/Zip/Country: Phone/Fax: Email: Please check here if you plan to stay for lunch on the 25th _____. Return completed form to: (deadline October 14, 1994) Donna Smith, Conference Coordinator 422 Theory Center Cornell University Ithaca, NY 14853 607-254-8686; 607-254-8888 (fax) donna@tc.cornell.edu From jeanne@TC.Cornell.EDU Mon Jul 18 13:56:06 1994 Received: from taboo.tc.cornell.edu for jeanne@TC.Cornell.EDU by www.ccl.net (8.6.9/930601.1506) id NAA26350; Mon, 18 Jul 1994 13:13:41 -0400 Received: (from jeanne@localhost) by taboo.tc.cornell.edu (8.6.9/8.6.6) id NAA58164; Mon, 18 Jul 1994 13:06:59 -0400 Date: Mon, 18 Jul 1994 13:06:59 -0400 From: "Jeanne C. Butler" Message-Id: <199407181706.NAA58164@taboo.tc.cornell.edu> To: symp-announce@TC.Cornell.EDU Subject: NIH Symposium Announcement Cc: jeanne@TC.Cornell.EDU X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X X-X X-X X-X X-X X-X CORNELL THEORY CENTER SYPMOSIUM X-X X-X COMPUTATION IN BIOPHYSICAL CHEMISTRY X-X X-X OCTOBER 25 - 26, 1994 X-X X-X X-X X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X-X ABSTRACT: The Cornell Theory Center announces the second in its series of symposia featuring research related to its Parallel Processing Resource for Biomedical Scientists. The Computation in Biophysical Chemistry Symposium will feature an international roster of speakers, and include a poster session and video theatre. WHO WE ARE: The Cornell Theory Center is a national high performance computing and communications resource, as well as an interdisciplinary research center located at Cornell University in Ithaca, NY. The National Institutes of Health awarded funding to the Cornell Theory Center in 1992 to create a resource that applies expertise in parallel computation and algorithm development to biomedical applications. CONFIRMED SPEAKERS INCLUDE: Dr. Jeffrey Skolnick, The Scripps Research Institute Dr. Joel Sussman, Weizmann Institute of Science, Israel & Brookhaven National Laboratory Dr. Guy Montelione, Rutgers University Dr. Harel Weinstein, Mt. Sinai School of Medicine Dr. Harold Scheraga, Cornell University Dr. Arnold Hagler, BioSym Technologies, Inc. Dr. Michael Teter, Corning, Inc. Dr. Ron Elber, University of Illinois at Chicago, and The Hebrew University, Israel Dr. Zhijun Wu, Argonne National Laboratory POSTER SESSION/VIDEO THEATRE: To apply for a poster session and/or video theatre presentation, please send abstract of research to Linda Callahan at cal@tc.cornell.edu by September 23, 1994. HOTEL ACCOMMODATIONS Blocks of rooms have been reserved at the following hotels: Collegetown Motor Lodge 312 College Avenue Ithaca, NY 14850-4624 phone: 607-273-3542 email: reservations@c-town.com rates: $56 - 69 per night Sheraton Inn One Sheraton Drive Triphammer Road and Route 13 Ithaca, NY 14850 phone: 607-257-2000 rate: $65 - 73 per night REGISTRATION: For registration information, send e-mail to donna@tc.cornell.edu or return the form below: Detach here ------------------------------------------------------------------------------- COMPUTATION IN BIOPHYSICAL CHEMISTRY SYMPOSIUM Name: Title: Organization: Address: City/State/Zip/Country: Phone/Fax: Email: Please check here if you plan to stay for lunch on the 25th _____. Return completed form to: (deadline October 14, 1994) Donna Smith, Conference Coordinator 422 Theory Center Cornell University Ithaca, NY 14853 607-254-8686; 607-254-8888 (fax) donna@tc.cornell.edu From elewars@alchemy.chem.utoronto.ca Mon Jul 18 14:55:40 1994 Received: from alchemy.chem.utoronto.ca for elewars@alchemy.chem.utoronto.ca by www.ccl.net (8.6.9/930601.1506) id OAA01330; Mon, 18 Jul 1994 14:17:21 -0400 Received: from localhost (elewars@localhost) by alchemy.chem.utoronto.ca (8.6.4/8.6.4) id OAA22654 for chemistry@ccl.net; Mon, 18 Jul 1994 14:17:24 -0400 Date: Mon, 18 Jul 1994 14:17:24 -0400 From: "E. Lewars" Message-Id: <199407181817.OAA22654@alchemy.chem.utoronto.ca> To: chemistry@ccl.net Subject: Books that show how to do ab in optimizations Jonathon Stevens asks about books that tell you how to do ab in opt's. Some recent books are A Spartan Tutoria, W. J. Hehre, L. D. Burke, and A. J. Shusterman This is supplied with the Spartan MM/Semiemp/Ab In computational program. If you don't have Spartan (so much the worse for you), you may still find the tutorial helpful with other programs. Practical Strategies for Electronic Structure Calculations, W. J. Hehre, L. D. Burke Evaluation of Modern Electronic Structure Methods, W. J. Hehre Experiments in Computational Organic Chemistry W. J. Hehre, L. D. Burke, A. J. Shusterman and W. J. Pietro All four are published by Wavefunction, Inc, 18401 Von Karman Ave Suite 370, Irvine CA 92715 (714)955-2120, FAX (714)955-2118) They are oriented toward the use of the highly graphical Spartan program of Wavefunction. Another useful book, designed for instruction in the Gaussian programs (G92 in particular) is Exploring Chemistry with Electronic Structure Methods, by James B. Foresman and Aeleen Frisch, available from Gaussian Inc., 4415 Fifth Ave, Pittsburgh, PA 15213, (412)279-6700, FAX ....-2118; info@gaussian.com All these books apeared in the last year or two. ==== Errol Lewars === From shepard@dirac.tcg.anl.gov Mon Jul 18 15:54:27 1994 Received: from dirac.tcg.anl.gov for shepard@dirac.tcg.anl.gov by www.ccl.net (8.6.9/930601.1506) id PAA04068; Mon, 18 Jul 1994 15:00:17 -0400 Received: by dirac.tcg.anl.gov (4.1/SMI-4.1) id AA04651; Mon, 18 Jul 94 14:00:34 CDT Date: Mon, 18 Jul 94 14:00:34 CDT From: shepard@dirac.tcg.anl.gov (Ron Shepard) Message-Id: <9407181900.AA04651@dirac.tcg.anl.gov> To: chemistry@ccl.net, desmarai@CHIMCN.UMontreal.CA Subject: Re: CCL:G9x, CISD... Help needed! Cc: shepard@tcg.anl.gov >If I do get it well the so called E(CISD) is giving by >the following formula: > > E(CISD) = E0 + Ecorr > >where E0 is the HF energy and > > Ecorr = SUM C_s * > s>0 > >where s represent the single and double excitation >(but really only the double since Brillouin Theorem lose all > single contribution in this case). In this equation, the >value of the CI expansion coefficient of the HF determinant is >1.0. > >As far as I know the real CISD energy should be: > > E(CISD) = C0^2*E0 + Ecorr > >with > > Ecorr = 2*SUM C_s*C_t > s >where s could be the ground state (but not t), and, of >course, Brillouin Theorem still lose some single contribution >(the one that couple with the ground state). > >So Am I missing something here or what? Both equations are correct. The first is a transition energy expression, the last is the expectation value expression. The connection between them is the eigenvalue equation, HC=CE. Taking the first row gives H(0,0)*C(0) + Sum(i) H(0,i)*C(i) = C(0)*E Dividing by C(0), or more conventionally using intermediate normalization with C(0)=1, and recognizing that E0=H(0,0) gives the first equation. Your second equation gives the expectation value for arbitrary expansion vector C, whereas the first, as written, is valid only for an eigenvector C using intermediate normalization. For HF orbitals, you are correct that the H(0,i) corresponding to single excitations are zero, but this condition is not necessary in order to establish the connection between the two energy expressions. $.02 -Ron Shepard From pburbano@Zellar.Vantage.GTE.COM Mon Jul 18 17:54:26 1994 Received: from Sneetches.Vantage.GTE.COM for pburbano@Zellar.Vantage.GTE.COM by www.ccl.net (8.6.9/930601.1506) id RAA12016; Mon, 18 Jul 1994 17:12:35 -0400 Received: from Zellar.Vantage.GTE.COM by Sneetches.Vantage.GTE.COM (4.1/SMI-4.1) id AA01830; Mon, 18 Jul 94 17:09:12 EDT Received: by Zellar.Vantage.GTE.COM with Microsoft Mail id <2E2B1A7D@Zellar.Vantage.GTE.COM>; Mon, 18 Jul 94 17:12:45 PDT From: Burbano Patricio To: "'smtp: chemistry@ccl.net'" Subject: information about polyAluminum Cloride Date: Mon, 18 Jul 94 17:07:00 PDT Message-Id: <2E2B1A7D@Zellar.Vantage.GTE.COM> Encoding: 5 TEXT X-Mailer: Microsoft Mail V3.0 Would anybody be able to give me a hand in finding information about how to produce Poly Aluminum Cloride? Thanks a lot.