From jkl@ccl.net Wed Apr 19 01:31:12 1995 Received: for jkl@ccl.net by www.ccl.net (8.6.10/930601.1506) id BAA17844; Wed, 19 Apr 1995 01:27:43 -0400 Date: Wed, 19 Apr 1995 01:27:43 -0400 From: Jan Labanowski Message-Id: <199504190527.BAA17844@www.ccl.net> To: chemistry@ccl.net Subject: Workshops at PSC Cc: jkl@ccl.net The following workshops at PSC have been announced: --------------------------------------------------- NUCLEIC ACID AND PROTEIN SEQUENCE ANALYSIS WORKSHOP FOR BIOMEDICAL RESEARCHERS Pittsburgh, Pennsylvania June 4-9, 1995 --------------------------------------------------- STRUCTURE DETERMINATION FROM NMR Pittsburgh Supercomputing Center June 25-28, 1995 --------------------------------------------------- METHODS OF MOLECULAR MECHANICS AND DYNAMICS OF BIOPOLYMERS" WORKSHOP Pittsburgh Supercomputing Center August 16-19, 1995 --------------------------------------------------- To find more about these (and other) workshops access the file "conferences" in the /pub/chemistry/info directory in CCL archives. You can get there via anon. ftp to www.ccl.net, via gopher gopher.ccl.net (port 73), via e-mail by sending a message: select chemistry cd info limit 400kB size 60 kB get conferences quit to MAILSERV@ccl.net or you can get there via Web through CCL home page: http://www.ccl.net/chemistry.html Dr. Jan K. Labanowski, Senior Research/Supercomputer Scientist/Specialist, etc. Ohio Supercomputer Center, 1224 Kinnear Rd, Columbus, OH 43212-1163 ph:(614)-292-9279, FAX:(614)-292-7168, E-mail: jkl@ccl.net JKL@OHSTPY.BITNET From lrbu00@xd88.kodak.com Wed Apr 19 10:01:19 1995 Received: from kodakr.kodak.com for lrbu00@xd88.kodak.com by www.ccl.net (8.6.10/930601.1506) id KAA22991; Wed, 19 Apr 1995 10:00:20 -0400 From: Received: from euler.kodak.com by kodakr.kodak.com with SMTP id AA17755 (5.67b/IDA-1.5 for <@kodakr.Kodak.COM:chemistry@ccl.net>); Wed, 19 Apr 1995 09:59:40 -0400 Received: from xd88.kodak.com by euler.kodak.com via SMTP (931110.SGI/931108.SGI.ANONFTP) for @kodakr.Kodak.COM:chemistry@ccl.net id AA16860; Wed, 19 Apr 95 09:59:39 -0400 Received: by xd88.kodak.com (AIX 3.2/UCB 5.64/4.03) id AA13689; Wed, 19 Apr 1995 09:45:52 -0400 Date: Wed, 19 Apr 1995 09:45:52 -0400 Message-Id: <9504190945.ZM13943@xd88.kodak.com> X-Mailer: Z-Mail (3.0.0 15dec93) To: chemistry@ccl.net Subject: New Semi-Empirical Parameterisations Cc: mckelvey@kodakr.kodak.com Mime-Version: 1.0 Encoding: 2 TEXT BOUNDARY, 13 MESSAGE, 2 TEXT BOUNDARY, 108 MESSAGE, 3 TEXT BOUNDARY Content-Type: multipart/mixed; boundary="PART-BOUNDARY=.19504190945.ZM13943.kodak.com" -- --PART-BOUNDARY=.19504190945.ZM13943.kodak.com Encoding: 10 TEXT Content-Type: text/plain; charset=us-ascii -- John M. McKelvey email: mckelvey@Kodak.COM Computational Science Laboratory phone: (716) 477-3335 2nd Floor, Bldg 83, RL Eastman Kodak Company Rochester, NY 14650-2216 -- --PART-BOUNDARY=.19504190945.ZM13943.kodak.com Encoding: 103 text X-Zm-Content-Name: agenda.txt Content-Description: plain text Content-Type: text/plain ; charset=us-ascii New Parameterisations in Semi-Empirical Methods Fall ACS Meeting, Chicago August 22/23, 1995 Tuesday, 22 August 1:40 Introductory Remarks J. McKelvey, Chair Research Labs, Eastman Kodak Co., Rochester, N.Y. 14650-2216 1:45 "Semi-Empirical Methods: An Overview" Walter Thiel, Organisch-chemisches Institut, Universitat Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland 2:15 "Developing A Semiempirical Method" J. J. P. Stewart, Stewart Computational Chemistry, 15210 Paddington Circle Colorado Springs, CO 80921-2512 2:45 coffee 3:00 "Semi-Empirical Models for Transition Metals" W. J. Hehre Chemistry Dept., University of Ca., Irvine, Irvine, CA 92717; Wavefunction, Inc, 18401 Von Karman Ave, Suite 370, Irvine, CA 92715 3:45 "Semi-Empirical Calculations of f Electron Systems" Michael C. Zerner, Quantum Theory Project, Williamson Hall, University of Florida, Gainesville, FL 32611 4:30 "Use of Semi-Empirical Methods in Direct Dynamics Calculations" Donald Truhlar, Chemistry Department, University of Minnesotta, Minneapolis, Minnesota 55455 Wednesday, 23 August 9:00 "Building a Bridge Between Ab Initio and Semiempirical Theories of Molecular Electronic Structure" Karl F. Freed, The James Frank Institute University of Chicago, Chicago, IL 60637 9:40 "New Developments In Semi-Empirical Methods" Walter Thiel, Organisch-chemisches Institut, Universitat Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland 10:25 coffee 10:40 "SAM1 Semi-Empirical Parameters for Transition Metals" Andrew Holder, Chemistry Department, University Of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, MO 11:20 "Parameterisation and Application of SINDO1" Karl Jug, Theoretical Chemistry, University of Hannover, Am Kleinen Felde 30, D-30167 Hannover, Germany 12:05 Lunch 1:45 "Development of an Atom-Typed NDO Scheme for NMR Predictions" Neil S. Ostlund, HyperCube, Inc, 419 Phillip St., Waterloo, Ontario, Canada 2:30 "COSMO-RS: Calculation of Chemical Potentials Based on Semi-Empirical MO-Calculations" Andreas Klamt, Bayer AG, D-51368 Leverkusen, Germany 3:15 coffee 3:30 "New Semi-Empirical Methods for Molecular Modeling in in the Condensed Phase" Chris Cremer, Chemistry Department, University of Minnesotta, Minneapolis, Minnesota 55455 4:15 "Improving Numerical SCRF Techniques for Ground and Excited States" Timothy Clark, Institut fur Organische Chemie der Friedrich-Alexander-Universitat Erlangen-Nurnberg, Henkestrasse 42, D-91054 Erlangen, Germany --PART-BOUNDARY=.19504190945.ZM13943.kodak.com-- From IRIKURA@ENH.NIST.GOV Wed Apr 19 10:16:29 1995 Received: from ENH.NIST.GOV for IRIKURA@ENH.NIST.GOV by www.ccl.net (8.6.10/930601.1506) id KAA23155; Wed, 19 Apr 1995 10:06:51 -0400 From: Received: from ENH.NIST.GOV by ENH.NIST.GOV (PMDF V4.2-13 #4653) id <01HPIOXBSMXS00HT7T@ENH.NIST.GOV>; Wed, 19 Apr 1995 10:03:04 EST Date: Wed, 19 Apr 1995 10:03:04 -0500 (EST) Subject: Force constants in redundant internal coordinates? To: chemistry@ccl.net Message-id: <01HPIOXBTZ5U00HT7T@ENH.NIST.GOV> X-PS-Qualifiers: /LEFT_MARGIN=6/SIZE=11 X-VMS-To: IN%"chemistry@ccl.net" X-VMS-Cc: IRIKURA MIME-version: 1.0 Content-type: TEXT/PLAIN; CHARSET=US-ASCII Content-transfer-encoding: 7BIT Is there a program (or literature reference) to convert cartesian force constants into force constants in full redundant internal coordinates? By this I mean a force constant for every bond, every bond angle, and every torsion, for a total in excess of 3N-6. The results are of interest to one of the spectroscopists here at NIST, and he wants to avoid re-inventing the wheel. I believe the stretches are of special interest. Any help will be appreciated! Karl Irikura ---------------------------------------------- Dr. Karl Irikura Chemical Kinetics and Thermodynamics Division National Institute of Standards and Technology Gaithersburg, MD 20899 ---------------------------------------------- From mfrancl@cc.brynmawr.edu Wed Apr 19 13:01:24 1995 Received: from cc.brynmawr.edu for mfrancl@cc.brynmawr.edu by www.ccl.net (8.6.10/930601.1506) id MAA26700; Wed, 19 Apr 1995 12:53:48 -0400 From: Received: by cc.brynmawr.edu (5.65/DEC-Ultrix/4.4) id AA10298; Wed, 19 Apr 1995 12:54:46 -0400 Date: Wed, 19 Apr 1995 12:54:46 -0400 Message-Id: <9504191654.AA10298@cc.brynmawr.edu> To: chemistry@ccl.net Subject: bug in G92 calculation of corrections for enthalpies Has anyone else noticed that G92 doesn't correct calculate the H-H(0) corrections (the thermal energies)? They can be off by as much as a factor of 10! The problem appears to be in the calculation of the vibrational contribution. Since we can duplicate the JANAF data, I assume we are doing the calculation correctly. Michelle M. Francl Associate Professor of Chemistry Bryn Mawr College Bryn Mawr, PA 19010 Phone: 610-526-5108 FAX: 610-526-5086 Internet: mfrancl@cc.brynmawr.edu From m10!frisch@uunet.uu.net Wed Apr 19 15:31:23 1995 Received: from relay3.UU.NET for m10!frisch@uunet.uu.net by www.ccl.net (8.6.10/930601.1506) id PAA29832; Wed, 19 Apr 1995 15:18:01 -0400 Received: from uucp2.UU.NET by relay3.UU.NET with SMTP id QQymef07077; Wed, 19 Apr 1995 15:17:54 -0400 Message-Id: Received: from m10.UUCP by uucp2.UU.NET with UUCP/RMAIL ; Wed, 19 Apr 1995 15:17:54 -0400 Received: by m10.gaussian.com; Wed, 19 Apr 95 15:01:40 EDT Date: Wed, 19 Apr 95 15:01:40 EDT From: m10!frisch@uunet.uu.net (Michael Frisch) Subject: Re: CCL:bug in G92 calculation of corrections for enthalpies To: chemistry@ccl.net In-Reply-To: , Wed, 19 Apr 1995 12:54:46 -0400 Has anyone else noticed that G92 doesn't correct calculate the H-H(0) corrections (the thermal energies)? They can be off by as much as a factor of 10! The problem appears to be in the calculation of the vibrational contribution. Since we can duplicate the JANAF data, I assume we are doing the calculation correctly. We've certainly checked these by hand. There are different conventions for different purposes, so perhaps you could be more specific about what you're doing and what you expect the program is doing. Mike Frisch ------- From mfrancl@cc.brynmawr.edu Wed Apr 19 16:31:24 1995 Received: from cc.brynmawr.edu for mfrancl@cc.brynmawr.edu by www.ccl.net (8.6.10/930601.1506) id QAA01008; Wed, 19 Apr 1995 16:20:32 -0400 From: Received: by cc.brynmawr.edu (5.65/DEC-Ultrix/4.4) id AA23673; Wed, 19 Apr 1995 16:21:24 -0400 Date: Wed, 19 Apr 1995 16:21:24 -0400 Message-Id: <9504192021.AA23673@cc.brynmawr.edu> To: chemistry@ccl.net Subject: G92 corrections to the enthalpy The solution to the mystery of the irreproducible numbers in G92: The key is in a footnote on pg. 115 of Foresman and Frisch "Exploring Chemistry with Electronic Structure Methods" where it says that the zero point energy is folded into the vibrational part of the H-H(0). I was assuming that the corrections listed in the G92 output table under the heading "thermal energies"were the H-H(0) corrections (they are for the translational and rotational parts) and was adding in the zero point energy separately. Since the G92 documentation refers you to the equations in McQuarrie -- where ZPE is NOT considered part of the thermal energy, but an entirely separate correction term -- my assumption seemed reasonable. Mystery solved - thanks to all who responded! Michelle M. Francl Associate Professor of Chemistry Bryn Mawr College Bryn Mawr, PA 19010 Phone: 610-526-5108 FAX: 610-526-5086 Internet: mfrancl@cc.brynmawr.edu From ar1z+@andrew.cmu.edu Wed Apr 19 17:01:25 1995 Received: from andrew.cmu.edu for ar1z+@andrew.cmu.edu by www.ccl.net (8.6.10/930601.1506) id QAA01676; Wed, 19 Apr 1995 16:54:53 -0400 Received: (from postman@localhost) by andrew.cmu.edu (8.6.12/8.6.9) id QAA21995; Wed, 19 Apr 1995 16:54:44 -0400 Received: via switchmail; Wed, 19 Apr 1995 16:54:43 -0400 (EDT) Received: from unix7.andrew.cmu.edu via qmail ID ; Wed, 19 Apr 1995 16:52:47 -0400 (EDT) Received: from unix7.andrew.cmu.edu via qmail ID ; Wed, 19 Apr 1995 16:52:36 -0400 (EDT) Received: from mms.4.60.Jan.26.1995.18.44.27.pmax.ul4.EzMail.2.0.CUILIB.3.45.SNAP.NOT.LINKED.unix7.andrew.cmu.edu.pmax.ul4 via MS.5.6.unix7.andrew.cmu.edu.pmax_ul4; Wed, 19 Apr 1995 16:52:36 -0400 (EDT) Message-ID: <8jZLUIi00WB88DHVkO@andrew.cmu.edu> Date: Wed, 19 Apr 1995 16:52:36 -0400 (EDT) From: "Alexander J. Ropelewski" To: Outbound News Subject: CCL:STRUCTURE DETERMINATION FROM NMR Cc: Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , rna@net.bio.net, chemistry@ccl.net, Outbound News , str-nmr@net.bio.net, bruker-users-mail@bloch.cchem.berkeley.edu, ammrl-request@bloch.cchem.berkeley.edu STRUCTURE DETERMINATION FROM NMR Pittsburgh Supercomputing Center June 25-28, 1995 Pittsburgh Supercomputing Center (PSC) is offering biomedical researchers a "Structure Determination From NMR" Workshop. The objective is to introduce participants to the different techniques for the elucidation of solution structures of biological macromolecules from nuclear magnetic resonance data. The workshop is free to academic participants. The worskhop will consist of lectures and extensive hands-on sessions. The programs AMBER, Mardigras and MidasPlus will be discussed. Hands-on sessions will be emphasized. Participants will be able to work on the examples provided or on their own experimental data. No prior supercomputing experience is necessary. Workshop leaders are: Dr. David Case, The Scripps Research Institute; and Drs Thomas James, Julie Newdoll and Uli Schmitz, University of California, San Francisco. This workshop is funded by a grant from the Biomedical Research Technology Program, National Center for Research Resources, National Institutes of Health. TRAVEL, MEALS AND HOTEL ACCOMMODATIONS FOR RESEARCHERS AFFILIATED WITH U.S. ACADEMIC INSTITUTIONS ARE SUPPORTED BY THIS GRANT. Enrollment is limited to 20. An application form is included. Deadline for applications is April 28, 1995. Additional information about this workshop can be found in http://pscinfo.psc.edu/biomed/workshops95.html * * * * * * * * * * PITTSBURGH SUPERCOMPUTING CENTER BIOMEDICAL INITIATIVE STRUCTURE DETERMINATION FROM NMR June 25-28, 1995 APPLICATION Name:________________________________________________________________________ Affiliation:_________________________________________________________________ Address:_____________________________________________________________________ (Business) _____________________________________________________________________________ ____________________________________________________________________________ (Home) ____________________________________________________________________________ Telephone: ____________________ ______________________ (Business) (Home) *Social Security Number: _______-_____-_______ Citizenship: ____________ Electronic Mail Address:____________________________________________________ Status: ___Graduate ___Post-doctoral Fellow ___Faculty ___Other (specify) Please indicate specifically any special housing, transportation or dietary arrangements you will need: _______________________________________________ How did you learn about this workshop? _____________________________________ REQUIREMENTS: Applicants must submit a completed application form and a cover letter. The letter should describe, in one or two paragraphs, your current research and how participating in the workshop will enhance this research. Please include a brief statement describing your level of experience with computers. Faculty members, staff and post-docs should provide a curriculum vita. Graduate students must have a letter of recommendation from a faculty member. Please return all application materials by APRIL 28, 1995 to: Biomedical Workshop Applications Committee Pittsburgh Supercomputing Center 4400 Fifth Avenue, Suite 230C Pittsburgh, PA 15213 Direct inquiries to: Nancy Blankenstein, blankens@psc.edu or 412/268-4960. *Disclosure of Social Security Number is voluntary. PSC does not discriminate on the basis of race, color, religion, sex, age, creed, national or ethnic origin, or handicap. From ar1z+@andrew.cmu.edu Wed Apr 19 17:01:28 1995 Received: from po7.andrew.cmu.edu for ar1z+@andrew.cmu.edu by www.ccl.net (8.6.10/930601.1506) id QAA01555; Wed, 19 Apr 1995 16:50:17 -0400 Received: (from postman@localhost) by po7.andrew.cmu.edu (8.6.12/8.6.9) id QAA15612; Wed, 19 Apr 1995 16:50:10 -0400 Received: via switchmail; Wed, 19 Apr 1995 16:50:09 -0400 (EDT) Received: from unix7.andrew.cmu.edu via qmail ID ; Wed, 19 Apr 1995 16:49:26 -0400 (EDT) Received: from unix7.andrew.cmu.edu via qmail ID ; Wed, 19 Apr 1995 16:49:09 -0400 (EDT) Received: from mms.4.60.Jan.26.1995.18.44.27.pmax.ul4.EzMail.2.0.CUILIB.3.45.SNAP.NOT.LINKED.unix7.andrew.cmu.edu.pmax.ul4 via MS.5.6.unix7.andrew.cmu.edu.pmax_ul4; Wed, 19 Apr 1995 16:49:08 -0400 (EDT) Message-ID: Date: Wed, 19 Apr 1995 16:49:08 -0400 (EDT) From: "Alexander J. Ropelewski" To: Outbound News Subject: CCL:Methods of Molecular Mechanics and Dynamics of Biopolymers workshop Cc: Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , Outbound News , rna@net.bio.net, chemistry@ccl.net "METHODS OF MOLECULAR MECHANICS AND DYNAMICS OF BIOPOLYMERS" WORKSHOP Pittsburgh Supercomputing Center August 16-19, 1995 The Pittsburgh Supercomputing Center (PSC) is hosting a workshop on "Methods of Molecular Mechanics and Dynamics of Biopolymers," August 16-19, 1995. The workshop will familiarize biomedical researchers with computational methods and provide practice in applying supercomputing resources to problems of concern in molecular mechanics. Practical experience on our supercomputers will be gained in the application to: (1) the theory and practice of molecular mechanics and dynamics; (2) the development and refinement of molecular mechanics force fields; (3) the problem of conformation mapping and analysis of polypeptide structures, including the refinement of structure from measured NMR data; and (4) computation of interaction energies and free energies for protein-drug interactions and conformational thermodynamics. Workshop leaders are Dr. Charles L. Brooks III, The Scripps Research Institute and Dr. Alexander D. MacKerell Jr., University of Maryland at Baltimore. The worskhop will consist of lectures and extensive hands-on sessions. General aspects of molecular mechanics software will be discussed and a number of packages are available for use at the PSC. However, the programs CHARMM and QUANTA will be utilized most extensively in demonstrations. Hands-on sessions will be emphasized. Participants will be able to work on the examples provided or on their own experimental data. No prior supercomputing experience is necessary. This workshop is funded by a grant from the Biomedical Research Technology Program, National Center for Research Resources, National Institutes of Health. TRAVEL, MEALS AND HOTEL ACCOMMODATIONS FOR RESEARCHERS AFFILIATED WITH U.S. ACADEMIC INSTITUTIONS ARE SUPPORTED BY THIS GRANT. Enrollment is limited to 20. An application form is included. Deadline for applications is: June 22, 1995. Please direct inquires or send the following application form to blankens@psc.edu. Additional information about this workshop can be found in http://pscinfo.psc.edu/biomed/workshops95.html PITTSBURGH SUPERCOMPUTING CENTER BIOMEDICAL INITIATIVE ************************************** August 16-19, 1995 APPLICATION Name:________________________________________________________________________ Affiliation:_________________________________________________________________ Address:_____________________________________________________________________ (Business) _____________________________________________________________________________ ____________________________________________________________________________ (Home) ____________________________________________________________________________ Telephone: ____________________ ______________________ (Business) (Home) *Social Security Number: _______-_____-_______ Citizenship: ____________ Electronic Mail Address:____________________________________________________ Status: ___Graduate ___Post-doctoral Fellow ___Faculty ___Other (specify) Please indicate specifically any special housing, transportation or dietary arrangements you will need: _______________________________________________ How did you learn about this workshop? _____________________________________ REQUIREMENTS: Applicants must submit a completed application form and a cover letter. The letter should describe, in one or two paragraphs, your current research and how participating in the workshop will enhance this research. Please include a brief statement describing your level of experience with computers. Faculty members, staff and post-docs should provide a curriculum vita. Graduate students must have a letter of recommendation from a faculty member. Please return all application materials by June 22, 1995 to: Biomedical Workshop Applications Committee Pittsburgh Supercomputing Center 4400 Fifth Avenue, Suite 230C Pittsburgh, PA 15213 Direct inquiries to: Nancy Blankenstein, blankens@psc.edu or 412/268-4960. *Disclosure of Social Security Number is voluntary. PSC does not discriminate on the basis of race, color, religion, sex, age, creed, national or ethnic origin, or handicap. From m10!frisch@uunet.uu.net Wed Apr 19 18:01:25 1995 Received: from relay3.UU.NET for m10!frisch@uunet.uu.net by www.ccl.net (8.6.10/930601.1506) id RAA02585; Wed, 19 Apr 1995 17:51:12 -0400 Received: from uucp6.UU.NET by relay3.UU.NET with SMTP id QQymep15588; Wed, 19 Apr 1995 17:51:05 -0400 Message-Id: Received: from m10.UUCP by uucp6.UU.NET with UUCP/RMAIL ; Wed, 19 Apr 1995 17:51:05 -0400 Received: by m10.gaussian.com; Wed, 19 Apr 95 17:47:06 EDT Date: Wed, 19 Apr 95 17:47:06 EDT From: m10!frisch@uunet.uu.net (Michael Frisch) Subject: G92 calculation of corrections for enthalpies To: chemistry@ccl.net In-Reply-To: Steen Hammerum , Wed, 19 Apr 1995 22:44:03 +0200 (METDST) > Has anyone else noticed that G92 doesn't correct calculate the H-H(0) > corrections (the thermal energies)? They can be off by as much as a factor > of 10! The problem appears to be in the calculation of the vibrational > contribution. Since we can duplicate the JANAF data, I assume we are doing > the calculation correctly. > > We've certainly checked these by hand. There are different conventions for > different purposes, so perhaps you could be more specific about what you're > doing and what you expect the program is doing. > > Mike Frisch Someone asked me to be more specific. Gaussian 92 produces thermal corrections which include vibrational energy in the harmonic approximation, (i.e., assuming a Boltzman distribution of vibrational states using the expressions from standard stat mech texts, such as McQuarrie's book), rotational energies assuming a rigid rotor (i.e., 3/2 kT) and translational energies (also 3/2 kT). Since most of the vibrational energy is zero-point energy, which is trivially verified, I don't see how this term or the overall thermal energy could be off by an order of magnitude. Partition functions are computed relative to both the bottom of the vibrational well and with respect to the lowest vibrational state. Which of these to use depends on whether your convention is to include the zero point terms in the activation barrier for a reaction or in the pre-factor when computing a reaction rate. Heat capacities also reported and are computed using expressions from McQuarrie's book. Neither of these quantities is relevent to computing reaction energies, enthalpies, or free energies. The original question referred to energies but also uses the expression H-H(0), so I don't know if the question refers to energies or enthalpies. Just in case, I'll comment on computing enthalpies. Gaussian 92 doesn't compute enthalpies at all. To convert the energy at a finite temperature to an enthalpy, one needs to know the Delta(PV) between the system and it's standard state. In practice, the easy thing to do is to compute a Delta-E for a reaction and then convert to a Delta-H of reaction by assuming an ideal gas and correcting by RT * Delta(N) (change in number of molecules in the reaction). Gaussian 94 does report an enthalpy, which is the energy at the requested temperature plus RT. This is not a Delta-H with respect to a standard state, but can be used to compute a Delta-H for a reaction by simply taking the algebraic sum of the enthalpies printed by the program for reactants and products, in which case the extra RT terms just automatically sum up to the RT * Delta(N) correction above. That's as much as I can say without knowing more specifically what the discrepancy in the orginal posting referrs to. Mike Frisch frisch@lorentzian.com -------