From dirk@rulglj.LeidenUniv.nl Sun Aug 29 14:08:31 1993 Received: from rulway.LeidenUniv.nl for dirk@rulglj.LeidenUniv.nl by oscsunb.ccl.net (5.65c+KVa/930601.1506) id AA20465; Sun, 29 Aug 1993 15:07:41 -0400 Received: from rulglj.LeidenUniv.nl by rulway.LeidenUniv.nl with SMTP id AA06645 (5.65c+/IDA-1.4.4 for <@rulway.LeidenUniv.nl:CHEMISTRY@ccl.net>); Sun, 29 Aug 1993 21:07:40 +0200 Received: by rulglj.LeidenUniv.nl (920330.SGI/920502.SGI) for @rulway.LeidenUniv.nl:CHEMISTRY@ccl.net id AA17938; Sun, 29 Aug 93 21:08:31 -0700 Date: Sun, 29 Aug 93 21:08:31 -0700 From: dirk@rulglj.LeidenUniv.nl (Dirk Huckriede) Message-Id: <9308300408.AA17938@rulglj.LeidenUniv.nl> To: CHEMISTRY@ccl.net Subject: Seeking contact Hello netters, I found this very interesting article: MEPSIM: A computational package for analysis and comparison of molecular electrostatic potentials. Ferran Sanz, Francesc Manaut, Jesus Rodriguez, Estrella Lozoya and Elena Lopez-de-Brinas J. Computer-Aided Molecular Design (1993), 337-347 I tried to contact the authors by ordinary mail-mail but I did not receive any response. Does someone have any experience with this MEPSIM program (the authors 'advertised' with it in their article), or does someone know an E-mail address of one of the authors or does anyone know one of the authors personally ? I could use it very well for my research. Any help will be appreciated ! Cheers, +-------------------------------+-----------------------------------+ | Dirk Huckriede | OH O | +-------------------------------+ | / \ | | | C --- C C --- Base | | Conformational Analysis Group | | | | | Gorlaeus Laboratories | C --- C | | Leiden University | | | | | | OH OH | +-------------------------------+-----------------------------------+ | P.O. Box 9502 Phone : +31 71 274505 | | 2300 RA Leiden Fax : +31 71 274488 | | The Netherlands E-mail : dirk@rulglj.leidenuniv.nl | +-------------------------------------------------------------------+ From ipcakc@vigyan.ernet.in Thu Aug 29 16:39:01 1993 Received: from relay2.UU.NET for ipcakc@vigyan.ernet.in by oscsunb.ccl.net (5.65c+KVa/930601.1506) id AA21546; Sun, 29 Aug 1993 16:48:11 -0400 Received: from spool.uu.net (via LOCALHOST) by relay2.UU.NET with SMTP (5.61/UUNET-internet-primary) id AA19904; Sun, 29 Aug 93 16:48:11 -0400 Received: from sangam.UUCP by uucp5.uu.net with UUCP/RMAIL (queueing-rmail) id 164619.2323; Sun, 29 Aug 1993 16:46:19 EDT Received: from vigyan.UUCP by sangam.ncst.ernet.in (4.1/SMI-4.2-ERNET-relay) with UUCP id AA22847; Sun, 29 Aug 93 21:37:39+0530 Received: by iisc.ernet.in (ERNET-IISc/AT&T UNIX SYS V.3.2) id AA00794; Sun, 29 Aug 93 22:43:16 EDT Received: by vigyan.iisc.ernet.in (smail2.3) id AA12570; 29 Aug 93 21:39:01 EST (Sun) To: CHEMISTRY@ccl.net Subject: NMR chemical shift Date: 29 Aug 93 21:39:01 EST (Sun) From: ipcakc@vigyan.iisc.ernet.in Message-Id: <9308292139.AA12570@vigyan.iisc.ernet.in> HI, CAN ANYBODY GIVE ME THE REFERENCES FOR CALCULATION OF NMR CHEMICAL SHIFT THEORETICALLY ? D. SENGUPTA . IISc Bangalore ipcakc@ipc.iisc.ernet.in From mxm@iris80.biosym.com Sun Aug 29 08:05:42 1993 Received: from bioc1.biosym.com for mxm@iris80.biosym.com by oscsunb.ccl.net (5.65c+KVa/930601.1506) id AA22453; Sun, 29 Aug 1993 18:05:44 -0400 Received: from iris80.biosym.com by bioc1.biosym.com (5.64/0.0) id AA13121; Sun, 29 Aug 93 15:05:44 -0700 Received: by iris80.biosym.com (920330.SGI/920502.SGI) for @bioc1.biosym.com:CHEMISTRY@ccl.net id AA28088; Sun, 29 Aug 93 15:05:42 -0700 Date: Sun, 29 Aug 93 15:05:42 -0700 From: mxm@biosym.com (Max Muir ) Message-Id: <9308292205.AA28088@iris80.biosym.com> To: CHEMISTRY@ccl.net Subject: finding transition states using MOPAC6.0 Dear CyberChemists, using MOPAC6.0 I have been attempting to correlate calculated heats of formation of some transition states with experimental activation energies for the following reaction H R1 R1 . \ / ./ tBu + C = C -------> tBu - CH2 - C / \ \ H R2 R2 I am getting some credible looking structures for the transition states. However, I cannot seem to get close to the saddle point, where the gradient normal is zero. I set SCFCRT=10^-12 and GNORM=0.0001, and the calculation exits normally thus- CYCLE: 9 TIME: 195.67 TIME LEFT: 356495.2 GRAD.: 0.000 HEAT: 4.288334 But when I do a FORCE calcn to verify the single -ve ROOT, MOPAC reports that GRADIENT NORM = 0.12229. I have one and one only negative root. What's the problem? What's the relationship between the GRAD reported in the line beginning 'CYCLE' and the 'GRADIENT NORM' resulting from the FORCE calculation. What do I need to do to improve my GRADIENT NORM? How good does it have to be for publication? tx, Max