From edvard@atf1.fagmed.uit.no Thu Sep 30 07:35:01 1993 Date: Thu, 30 Sep 93 07:35:01 GMT From: edvard@atf1.fagmed.uit.no (Oyvind Edvardsen Computer Graphics Lab. IMB Univ. Tromsoe) Message-Id: <9309300735.AA00479@atf1.fagmed.uit.no> To: chemistry@ccl.net Subject: Re: torsion energies in conjugated systems marty@ionchannel.med.harvard.edu wrote: > Does anyone know a forcefield which includes a term for >torsional energy in a conjugated system? Specifically, I am >interested in rotating the carbonyl in acetophenone out of plane >with the phenyl ring. MOPAC geometry optimization places the The way e.g. MMP2 handles this is to do 'pi-calculations' prior to the molecular mechanics energy minimization. From the 'pi-calcs' one get the bond order of the pi bonds. The bond orders are used to scale the bond force constants and the torsional barriers for the given pi bonds. Depending on the amount of rotation from 'normal', the bond order and hence the parameters are changed. I guess others have used this or similar approach. You may take a look at Burkert & Allinger: Molecular mechanics, ACS monograph 177 (1982), p. 52 and on... Disclaimer: I haven't used MMP2 for several years ... -oed. From Leif.Laaksonen@csc.fi Thu Sep 30 10:32:06 1993 Date: Thu, 30 Sep 1993 08:32:06 +0200 Message-Id: <199309300632.AA25558@csc.fi> To: chemistry@ccl.net From: Leif.Laaksonen@csc.fi Subject: Refrence to van der Waals radii for the elements Hi netters, All the molecular modelling packages (and many more) have a list of the van der Waals radii for the different elements. Of course there is no reference in any table. From where are these values collected? Yes I know about the paper by Bondi (JPC 68(1964)441) but there must be more. Thank you for your help. -leif laaksonen ------------------------------------------------------------------- Leif Laaksonen | Center for Scientific Computing | Phone: 358 0 4572378 P.O. Box 405 | Telefax: 358 0 4572302 FIN-02101 Espoo | Voice Mail: 358 486257407 FINLAND | Mail: Leif.Laaksonen@csc.fi NOBODY can write a thousand- word essay on what he did during the summer! It's ridiculous! Charlie Brown ------------------------------------------------------------------- From h.rzepa@ic.ac.uk Thu Sep 30 08:49:22 1993 Message-Id: <9309300752.AA09644@cscmgb.cc.ic.ac.uk> Date: Thu, 30 Sep 1993 08:49:22 +0000 To: CHEMISTRY@ccl.net From: h.rzepa@ic.ac.uk (Henry Rzepa) (Henry Rzepa) Subject: Re: What level to stop at > Doug Smith raises an interesting point with respect to the "adequate" >level of theory required for a given problem. To which Chris Cramer replied: > > I referee a lot of papers where the theory is simply presented as some >sort of burning-bush prophecy. For very specialized journals, this may be >appropriate insofar as it adds to the available database of computations >which may later be compared to each other and to experiment. It is entirely >inappropriate for general interest venues, where our goal should be to >illustrate how theory and experiment may be used synergistically. I can fully endorse that. Perhaps 70% of the papers that I referee made little or no reference to the state of the art, or try to justify their own choice of theoretical procedure. A high proportion also make only token reference to any experimental results. It is also common to present only one particular Hamiltonian, and then stick to the results produced without comparison with other methods. Where we quote for example semi-empirical results, we always try to do some ab initio comparison as well. On the other hand, the "convergence" problem can be overdone. Not only Diels-alder, but before that methylene, and now perhaps (???: to spare any blushes). Dr Henry Rzepa, Dept. Chemistry, Imperial College, LONDON SW7 2AY; rzepa@ic.ac.uk via Eudora 1.4, Tel:+44 71 225 8339, Fax:+44 71 589 3869. From ryan%phmms0.mms.smithkline.com@smithkline.com Thu Sep 30 04:51:50 1993 Date: Thu, 30 Sep 93 08:51:50 -0400 From: ryan%phmms0.mms.smithkline.com@phinet.smithkline.com (Dominic Ryan) Message-Id: <9309301251.AA07951@phmms0.mms.smithkline.com> To: chemistry@ccl.net Subject: Doug Smith's reviewer question. I think balance is certainly key but the correctness of the science should perhaps come first; Janet Del Bene's comments were right on the money balanced with the onus of the reviewer to ground complaints in scientific criticism. If the reviewer can state clearly that the method used has limitations that prevent the conclusions apparently drawn from being applicable then the reviewer needs to say so as Fred Van-Catledge pointed out. If the reviewer would have personally used a huge basis set but not fundamentally changed the results then it is to the researcher's credit for having obtained valid chemical insight with the most effecient use of resources. Throughout the history of science some of the best ideas and experiments have been very simple ones. It comes down to experimental justification. Unless trivially common knowledge, the resesearcher needs to include in the 'experimental' section appropriate referencing to support the application of the theory used to the problem at hand. If that is not possible then support of the necessary speculation is needed as well as providing a method of testing it. If it is a test of new methodology then whatever criteria of assessment are used (experimental data etc.) need to be referenced. In this manner what the researcher has available for resources becomes a separate question. If I wanted to prepare air-sensitive compounds but did not have access to a hood and vacuum line or glove-box then it might be a shame that I could not carry out the work I would like to, but that would not make it correct if I did anyway, which I suppose is just a paraphrasing of what Janet Del Bene said. However, computational chemistry is not quite so black and white, perhaps unfortunately, and it comes back to the researcher and reviewer to correctly determine the limits of what can be learned with what one had available. ___________________________________________________________________________ M. Dominic Ryan (215)-270-6529 SmithKline Beecham Pharmaceuticals Headers may be WRONG, do NOT use reply, use: ryan%phmms0.mms@smithkline.com From C867BUC%SEMOVM.BITNET@phem3.acs.ohio-state.edu Thu Sep 30 04:01:56 1993 Date: Thu, 30 Sep 1993 09:01:56 -0500 (CDT) From: "Anthony J. Duben" Subject: 1994 Summer Computer Simulation Conference To: chemistry@ccl.net Message-Id: <30SEP93.09755081.0087.MUSIC@SEMOVM> Second Reminder: Announcement of the 1994 Summer Computer Simulation Conference July 18-20, 1994 La Jolla CA Includes Categories and Sessions on: Molecular Simulation Molecular Nanotechnology and Molecular Manifacturing Artificial Intelligence Knowledge Based Systems Neural Networks Fuzzy Logic Deadlines: One page abstracts -- November 15, 1993 Abstract acceptance notice and Author Kit to be mailed -- Mid January 1994 Camera Ready manuscripts -- March 30, 1994 Mail abstracts/papers to: Society for Computer Simulation (SCSC94) 4838 Ronson Court, Suite L San Diego CA 92111-1810 voice (619) 277-3888 fax (619) 277-3930 e-mail: scs@sdsc.bitnet This announcement submitted to the network by Anthony J. Duben Southeast Missouri State University Computer Science Department, Mail Stop 6800 1 University Plaza Cape Girardeau MO 63701-4799 voice: (314) 651-2194 FAX: (314) 651-2791 bitnet: C867BUC@SEMOVM internet: C867BUC@SEMOVM.SEMO.EDU From smb@smb.chem.niu.edu Thu Sep 30 02:42:24 1993 Date: Thu, 30 Sep 93 07:42:24 -0500 From: smb@smb.chem.niu.edu (Steven Bachrach) Message-Id: <9309301242.AA25034@smb.chem.niu.edu> To: CHEMISTRY@ccl.net Subject: Re: reviewers/resources In regard to the reviewers/resource thread initiated by Doug Smith, I would like to strongly endorse Janet Del Bene's opinion: I do not believe that practicality is a justfication in this case. I tell my graduate students that we will use the LOWEST level of theory that is APPROPRIATE for the project. If we can trust a HF/6-31G* result then we stop there. If we need a CI calculation (or whatever) then we do that - if we have the available resources. If we cannot run the calculations we feel we can trust (i.e. have some belief that the results will strongly reflect experiment) then we drop the project and don't publish. I am tired of reading articles that are meaningless because the level of theory employed is totally inappropriate, and I have given negative reviews to people whose work could not be justified on this scientific basis - lack of resources does not mean we can publish what we've done. Wrong science is wrong science, regardless of whether it is the best we can do or not. On the other hand, and I think this is Doug's main point (correct me please if I'm wrong), if the researcher justifies the method and shows that larger basis sets, more ciorrelation, etc. will not significantly alter the results, then HIGHER levels of theory are a tremendous waste. But again, the burden is on the author to convince the scientific community that the problem has been approached at a level at which we can have confidence in the result. Also, as Janet Del Bene has pointed out, these comments apply just as well to experimentalists as theorists! I'm putting on my asbestos suit now... Steven Bachrach Department of Chemistry Northern Illinois University DeKalb, Il 60115 smb@smb.chem.niu.edu From chp1aa@surrey.ac.uk Thu Sep 30 16:08:34 1993 From: Mr Andrew D Allen Message-Id: <9309301511.AA19285@central.surrey.ac.uk> Subject: Conjugated systems and MM To: chemistry@ccl.net Date: Thu, 30 Sep 93 16:11:24 BST Pieter Stouten writes, Conjugated pi-systems constitute one of the larger issues in the development of force fields that describe macromolecule-drug interactions adequately. Anyone interested in this may like to contact M.J.Bearpark, M Olivucci or M.A.Robb who gave a lecture on "Large active space valence bond methods: application to conjugated polycyclic hydrocarbons" This theory takes an MM sigma framework then uses ab-initio parametering on top to modify the force constants, I could not follow most of the technical side of how this was done but the results looking promising. Email address: max@gandalf.ciam.unibo.it (Olivucci) udca700@oak.cc.kcl.ac.uk (M.A. Robb) no email for Bearpark. Andy. From jmcohen@cbda6.apgea.army.mil Wed Sep 29 08:23:17 1993 Date: Wed, 29 Sep 93 12:23:17 EDT From: Joel M. Cohen To: chemistry@ccl.net Subject: Re: looking for modelling position in pharmaceutical company Message-Id: <9309291223.aa02401@cbda6.apgea.army.mil> WITH REGARD TO: > Dear netters: > > I am interested in doing a survey of molecular modelling positions in pharmaceutical companies, especially > middle size (or large companies). Does anybody know what is an effective way for me to 1. find a background > description for these companies, how are they doing in the recent years 2. find out whether they have positions for > molecular modelling and what kind of modelers do they want ? > > Appreciated if you send your reply to the net, or to my email address. > > > Feng > HEY I'M LOOKING FOR WORK TOO. IF I HAD KNOWN IT WAS KOSHER TO DO THIS I'D HAVE DONE IT LONG AGO. Dr. Joel Cohen From mckelvey@Kodak.COM Thu Sep 30 07:50:47 1993 Date: Thu, 30 Sep 93 11:50:47 -0400 Message-Id: <9309301550.AA06825@Kodak.COM> From: mckelvey@Kodak.COM To: osc@Kodak.COM Subject: Forcefields and Conjugation and Dihedrals Force fields that include explcit conjugation effects in determining K(stretch), L0, and V2 have been extremely valuable here at Kodak for determining dihedral angles of extensively conjugated systems, namely MMX. This is the forcefield found in in PCMODEL from Serena Software, and available also in MODEL, from Kosta Steliou, now in Boston, I believe. MMX "nails" the dihedrals of biphenyl, o-Me biphenyl, and cisoid o,o'-dime biphenyl to within 1-2 degrees of experiment (42,58, and 72 degrees, respectively.) within 1-2 degrees of experiment (42,58, and 72 degrees, respectively.) It will show some effect on the torsion angle of biphenyl when substituted 4-no2,4'-nh2. It is easy to "tune the forcefiled if desired...it is editable in a flat file. Hope this is useful, inspite of missspelings. John McKelvey From rwoods@biop.ox.ac.uk Thu Sep 30 18:30:34 1993 Date: Thu, 30 Sep 1993 17:30:34 +0100 From: rwoods@biop.ox.ac.uk To: chemistry@ccl.net Message-Id: <0097353F.F84089E0.12806@biop.ox.ac.uk> Subject: Level of Theory Discussion Hello netters, Having read with interest the recent comments regarding the extent to which the level of theory should determine the acceptance or rejection of scientific papers I would like to (briefly) state a few of my thoughts. 1) I strongly empathize with Doug Smith's comments, and feel that simply stating that a calculation COULD be done at a higher level is not a sufficient reason for rejecting a paper. Just as an author should be able to justify the method, a reviewer should have a GOOD reason to doubt it. Clearly a lot depends on what the authors are trying to say about the data, ie what accuracy they are claiming. Ultimately, as Chris Cramer has pointed out, the work should be done at a level of theory that is converged with respect to the desired information. 2) Janet Del Bene has suggested that the "problem" should be reformulated so that an appropriate level of theory may be applied. I suggest that this is what computational chemists do most of the time. It is the best way to get trustworthy agreement with experiment (ie. non-fortuitous agreement). Unfortunately, the choice of suitable systems for comparison with experiment differs depending on the area of research. For example, in large biologically relevant systems most experimental data is determined in solution. In these systems it may be very difficult to estimate the accuracy of the computational method. Nonetheless every reasonable attempt should be made to ensure that the calculations have been performed as rigorously as possible, based on current knowledge. 3) Unfortunately, more complex problems often necessitate the application of a level of computation that is somewhat less that ideal. In these cases I think a lot of thought has to go in to deciding what is the best way to determine the accuracy of the computations. When calculations are performed at with a comparatively untested method, an onus is placed on the authors to determine the accuracy of their particular calculations. However, provided this is done the paper should not be rejected based on the level of the computation alone. Just my thoughts on the topic, Rob Woods ******************************************************************************** Robert J. Woods, Ph.D. Glycobiology Institute Department of Biochemistry University of Oxford South Parks Road Oxford, OX1 3QU ******************************************************************************** From CLETNER@DESIRE.WRIGHT.EDU Thu Sep 30 08:34:41 1993 Date: Thu, 30 Sep 1993 13:34:41 -0500 (EST) From: CLETNER@DESIRE.WRIGHT.EDU Subject: Re: reviewers & computational chemistry To: chemistry@ccl.net Message-Id: <01H3K79IFKTU003BMG@DESIRE.WRIGHT.EDU> My opinion... To think that a paper would be rejected because it does not carry out the most advanced calculation is crazy. The question needs to be does the computation answer the question asked. Afterall, isn't this what sciense is all about, asking questions and answering those questions. Computational chemistry is no different than any other type of chemistry (organic, bio, blah, blah, blah....) in terms of what is publishable and what isn't. Are we to believe that every "bench" experiment that was ever published was done at the highest level possible? Of course not. To restrict calculations to the highest level of theory is equivalent to requireing an experiment to be the most advance with no regard for what is really needed to answer the question asked. Charles Letner Department of Biochem. and Mol. Bio. Wright State University Dayton, OH 45435 e-mail: cletner@desire.wright.edu From POPUGURJ@sq.ehu.es Thu Sep 30 09:56:54 1993 Date: Thu, 30 Sep 1993 9:56:54 UTC+0100 From: Jesus Ugalde Subject: 2PDM To: chemistry@ccl.net Message-Id: <868*/S=POPUGURJ/OU=sq/O=ehu/PRMD=iris/ADMD=mensatex/C=es/@MHS> Dear netters We just have a long standing question about GAUSSIAN92. It was posed to GAUSSIAN Inc. long time ago, a year ago or even more, however we have got no answer from them. Maybe someone out there can help us. In particular we are interested in obtaining the two-particle-density-matrix (2PDM) from as many levels of theory as possible. Among the standard methods built-in GAUSSIAN92 , CISD and MPn are very desirable. Apparently GAUSSIAN 92 evaluates the 2PDM, however we do not know how to retrieve it. According to the PROGRAMMER's REFERENCE MANUAL, see page 615, iop(11/28=-4) seems to be solution to all our troubles. So we have tried a simple CISD on H2 with the minimal basis set (STO-3G) since for this case one can obtain "manually" the 2PDM form the one-particle-density-matrix and the molecular orbital coefficients. We have run two separate GAUSSIAN jobs, the former with iop(11/28=-1) to obtain the HF Density Matrices, mainly for checking puposes: The GAUSSIAN 92 job is --------------------------------------------------------- $RunGauss #cisd/sto-3g force iop(9/15=0,9/25=1,9/26=1,9/28=-1) iop(11/28=-1,11/29=10,11/33=3) pop=none units=au G90 hh prueba. 0,1 h h 1 1.4 --------------------------------------------------------- the output listing contains the 2PDM under the heading AO 2PDM, which is included below AO 2PDM, I= 1 J= 1: 1 2 1 .907989D-01 2 .181598D+00 .907989D-01 AO 2PDM, I= 2 J= 1: 1 2 1 .181598D+00 2 .363196D+00 .181598D+00 AO 2PDM, I= 2 J= 2: 1 2 1 .907989D-01 2 .181598D+00 .907989D-01 Indeed symmetry considerations have been taken into account for only 9 out of 16 matrix elements are listed, and it looks like each of the distinct elements have been listed multipled be the number of repetitions. However for the CISD 2PDM, i.e.:according to the manual iop(11/28=-4) we have run the following job. ------------------------------------------------------- $RunGauss #cisd/sto-3g force iop(9/15=0,9/25=1,9/26=1,9/28=-1) iop(11/28=-4,11/29=10,11/33=3) pop=none units=au G90 hh prueba. 0,1 h h 1 1.4 ------------------------------------------------------- Now, the output listing does also contain the heading AO 2PDM. Its content is given below AO 2PDM, I= 1 J= 1: 1 2 1 -.824132D-01 2 -.524246D-01 .945032D-01 AO 2PDM, I= 2 J= 1: 1 2 1 -.524246D-01 2 .203976D+00 -.524246D-01 AO 2PDM, I= 2 J= 2: 1 2 1 .945032D-01 2 -.524246D-01 -.824132D-01 However, this is not the 2PDM in the same sense as the HF one!!!. Just a simple "manual" calculation gives the following 2PDM's for the CISD/STO-3G H2: i j k l 2PDM-HF 2PDM-CI ----------------------------------------------- 1 1 1 1 .0907988868 .0715283035 1 1 1 2 .0907988868 .1100694702 1 1 2 1 .0907988868 .0692324892 1 1 2 2 .0907988868 .1123652844 1 2 1 1 .0907988868 .1100694702 1 2 1 2 .0907988868 .0715283035 1 2 2 1 .0907988868 .1123652844 1 2 2 2 .0907988868 .0692324892 2 1 1 1 .0907988868 .0692324892 2 1 1 2 .0907988868 .1123652844 2 1 2 1 .0907988868 .0715283035 2 1 2 2 .0907988868 .1100694702 2 2 1 1 .0907988868 .1123652844 2 2 1 2 .0907988868 .0692324892 2 2 2 1 .0907988868 .1100694702 2 2 2 2 .0907988868 .0715283035 Indeed it is easly confirmed, at least for the normalization check on both HF and CI 2PDM's, i.e.: do i=1,2 do j=1,2 do k=1,2 do l=1,2 hf=hf+2pdmhf(i,k,j,l)*s(i,j)*s(k,l) ci=ci+2pdmci(i,k,j,l)*s(i,j)*s(k,l) end do end do end do end do where the s-matrix is the usual overlap matrix. Both hf and ci normalize to the number of electron pairs, 1 in this case. Any comment or help will be most welcomed. Jesus M. Ugalde Phone: 34-43-216600 Prof. of Chemistry FAX: 34-43-216622 The University of the Basque Country P.O.Box 1072, 20080 Donostia EUSKADI, SPAIN From NMUELLER@EDVZ.UNI-LINZ.AC.AT Thu Sep 30 20:12:02 1993 Message-Id: <199309301812.AA14932@oscsunb.ccl.net> Date: Thu, 30 Sep 1993 19:12:02 +0100 To: chemistry@ccl.net From: NMUELLER@edvz.uni-linz.ac.at (Norbert Mueller) Subject: Re: torsion energies in conjugated systems Is there an "official" supported version of MMPI2? If so where can it be obtained from? I only know of MMPI. Thanks to anyone who has a pointer. -- Norbert Mueller Institut fuer Chemie Johannes Kepler Universitaet A-4040 Linz Austria e-mail: NMUELLER@edvz.uni-linz.ac.at (preferred) norbert@soft.uni-linz.ac.at (MacPost) NorbertM (AMDA-Link Linz) <-FirstClass NorbertM@AMDA.UNI-LINZ.AC.AT ->FirstClass From GUSTAVO@nickel.laurentian.ca Thu Sep 30 10:18:38 1993 Date: Thu, 30 Sep 1993 15:18:38 -0500 (EST) From: GUSTAVO@nickel.laurentian.ca Subject: Re.: van der Waals radii for the elements. To: chemistry@ccl.net Message-Id: <01H3KBCR2Q7M8ZDZ29@NICKEL.LAURENTIAN.CA> Hi, This is a follow-up to the question by Leif Laaksonen on the atomic radii. The overall situation on the use of radii is far from uniform: Bondi's radii (A. Bondi, J.Phys.Chem. 68 (1964) 441) and Pauling's radii (L. Pauling, The nature of the Chemical Bond, Cornell, Ithaca, 1960) are used sometimes, although nowadays there's some tendency to use the values given by Gavezzotti (A. Gavezzotti, JACS 105 (1983) 5220). The latest CRC Handbook of Chemistry and Physics will show slightly different values; other quoted source is: J.L. Finney, J. Mol. Biol. 96 (1975) 721. The experimental values depend on the property observed (critical constants, diffusion coefficients, etc) and the model used to interpret them. The same can be said for the radii computed from theory. [For some discussion of this and comparisons with radii derived from electron densities, see J.Comp.Chem. 12 (1991) 1198.] For some metals or unusual elements, the radii are commonly 'made-up', giving just a flat value for most of them. For *qualitative* analyses, these differences may matter little (e.g., when studying only the distribution of electrostatic potential over the van der Waals surface, solvent-accessible surface or the like). Quantitatively, the differences can be important. Thus, it might perhaps be better not to restrict analyses to a single surface but to give results estimated (or averaged) within a reasonable range of values of atomic radii. Hope this helps, G. Arteca --------------------------------------------------------------------- Gustavo A. Arteca Departement de Chimie et Biochimie, Laurentian University - Universite Laurentienne, Ramsey Lake Rd., Sudbury (Ontario), Canada P3E 2C6. Tel.: +1-(705) 675-1151 Ext. 2117 Fax : +1-(705) 675-4844 E.m : Gustavo@nickel.laurentian.CA --------------------------------------------------------------------- From adrian@silver.chem.nwu.edu Thu Sep 30 11:12:13 1993 From: adrian@silver.chem.nwu.edu (Adrian Roitberg) Message-Id: <9309302112.AA26054@silver.chem.nwu.edu> Subject: coordinates To: chemistry@ccl.net Date: Thu, 30 Sep 93 16:12:13 CDT Dear netters, I am looking for cartesian coordinates of an elusive but common transition metal complex. It is (NH_3)_5 Ru(II) 4-4'-bypiridyl Ru(III) (NH_3)_5 Do you know of anything on it out there ?? It is not in version of the Cambridge database that we have here. Thanks you very much for your answers. regards adrian Adrian E. Roitberg ============================================================================= Dept. of Chemistry | Phone: (708) 491-3423 Northwestern University | Fax : (708) 491-7713 2145 Sheridan Road. Evanston, IL |E-mail:adrian@silver.chem.nwu.edu 60208-3113 | ============================================================================= From lipkowitz@chem.iupui.edu Fri Oct 1 02:26:13 1993 Date: Thu, 30 Sep 1993 16:56:13 +0930 From: Lipkowitz Subject: Molecular Mechanics To: Comp Chem List Message-Id: <01H3KET5QAG20049O6@INDYVAX.IUPUI.EDU> Dear netters Theory is too important a tool to leave in the hands of theoreticians and, accordingly, we organic chemists have decided to use theory to help solve problems. I recently wrote a review article with Mike Peterson on applications of molecular mechanics in organic synthesis (to appear in Chem. Rev.,October?). It was evident to us that many of our synthetic colleagues were inadvertently abusing molecular mechanics, eg taking parameters from one force field for use in another, equating steric energies with free energies, neglecting the Curtin Hammett principle, etc, etc. I'd like to compile a list of flagrant (and not so flagrant) abuses of molecular mechanics. I'm interested in your responses. Could you send me a list of commonly found abuses of molecular mechanics that you've encountered? I don't want specific papers cited, but rather, problems in general. It would be interesting to prioritize the list with number 1 being the most grievous and the last entries being what you and I might call pet peeves. If the response is sufficient, I will post a summary to the net. Kenny Lipkowitz Professor of Chemistry IUPUI lipkowitz@chem.iupui.edu From jle@world.std.com Thu Sep 30 14:27:11 1993 Date: Thu, 30 Sep 1993 18:27:11 -0400 From: jle@world.std.com (Joe M Leonard) Message-Id: <199309302227.AA14224@world.std.com> To: chemistry@ccl.net Subject: Desktop non-workstations... Folks, Several of us were sitting and making statements about who uses what kinds of non-workstations at their desk. It seemed reasonable to ask folks this question... What's the machine on your desk (Mac, PC, etc)? If a Mac, (a) does it have an ethernet connection (b) do you run an X-emulator If a PC, (a) what OS is running (DOS, Windows, OS/2, Quarterdeck, NextStep, etc) (b) do you plan to change/update to something else (c) does it have an ethernet connection (d) do you run an X-emulator For everybody's sake, PLEASE PLEASE PLEASE don't reply to the forum - send all replies, etc to me directly. I'll summarize, but it's pointless to waste scads of bandwidth on this when individual emails will do... Thanks in advance, Joe Leonard jle@world.std.com P.S. Please reply if you're running something "unusual" - basically anything but multifinder on the mac, or DOS/Windows on the PC... From tropsha@gibbs.oit.unc.edu Thu Sep 30 16:29:08 1993 Date: Thu, 30 Sep 1993 16:27:34 +0501 (EDT) From: Alex Tropsha Subject: Re: Refrence to van der Waals radii for the elements To: Leif.Laaksonen@csc.fi Message-Id: A good recent reference is: Emsley, J. The Elements. Clarendon Press, Oxford, 1989.