From TSHEHLA@che.und.ac.za Wed Jan 10 01:47:16 1996 Received: from owl.und.ac.za for TSHEHLA@che.und.ac.za by www.ccl.net (8.6.10/950822.1) id BAA00201; Wed, 10 Jan 1996 01:34:28 -0500 Received: from ChemFS1.ChE.und.ac.za by owl.und.ac.za with SMTP (PP) id <11523-0@owl.und.ac.za>; Wed, 10 Jan 1996 08:33:59 +0200 Received: from CHEMENG/SpoolDir by che.und.ac.za (Mercury 1.21); 10 Jan 96 08:33:58 +0200 Received: from SpoolDir by CHEMENG (Mercury 1.21); 10 Jan 96 08:33:40 +0200 From: Tankiso Tshehla - PG Organization: University of Natal - Durban To: chemistry@www.ccl.net Date: Wed, 10 Jan 1996 08:33:34 SAST Subject: symmetry coordinates Priority: normal X-mailer: Pegasus Mail v3.22 Message-ID: <1F84BE05F3F@che.und.ac.za> Dear Netters and associates; Wish you all the best of 1996 and enjoyable networking. Can anyone with experience of vibrational analysis suggest some symmetry coordinates of the six intermolecular modes of the C2H4-HOH complex; the complex is a Cs type with one of the water H's interacting with the CC pi-orbitals and the "free" water OH bisecting the CC axis. I have visual representations of all the modes and from G92 output displacement coordinates I can figure out what the Intermolecular modes are like. I have tried all the options but there seems to be mixing of a' and a'' modes and I would like that to be completely removed i.e. free mixing. Thanking you all in advance T M Tshehla (As above so, Below). From owner-chemistry@ccl.net Wed Jan 10 06:47:21 1996 Received: from bedrock.ccl.net for owner-chemistry@ccl.net by www.ccl.net (8.6.10/950822.1) id GAA02661; Wed, 10 Jan 1996 06:42:55 -0500 Received: from Mailer.Uni-Marburg.DE for STAHL@ps1515.chemie.uni-marburg.de by bedrock.ccl.net (8.7.1/950822.1) id GAA29436; Wed, 10 Jan 1996 06:42:40 -0500 (EST) Received: from ps1515.Chemie.Uni-Marburg.DE by Mailer.Uni-Marburg.DE (AIX 3.2/UCB 5.64/20.07.94) id AA70097; Wed, 10 Jan 1996 12:42:13 +0100 Received: from NWS_CHEMIE/MAILQ by ps1515.chemie.uni-marburg.de (Mercury 1.20); 10 Jan 96 12:43:53 GMT+2 Received: from MAILQ by NWS_CHEMIE (Mercury 1.20); 10 Jan 96 12:43:27 GMT+2 To: chemistry@ccl.net From: "Martin Stahl" Date: Wed, 10 Jan 1996 12:43:24 MDT Subject: CCL:MM3 parameters for O-C-C-C(sp2) X-Pmrqc: 1 Priority: normal X-Mailer: WinPMail v1.0 (R1) Message-Id: Dear subscribers, I have been doing calculations on some rather simple organic compounds containing an alcoholic OH-group in 3-position to an sp2-hybridized carbon atom (a phenyl or a vinyl group, for example). I do the conformational analyses with macromodel and recalculate all energies by means of MM3(94). For such molecules, the energetic order of the low energy conformers is not confirmed by experiment, wehereas for the pure unsaturated hydrocarbons results agree very well with measured data. My first suspicion is that the weak hydrogen bond -like interaction between the acidic proton and the double bond, which is possible in some conformers, might play a role here. Has anyone come across a problem like this or even treated it within a force field? I am grateful for any hint. Martin Stahl