From chemistry-request@server.ccl.net Tue Oct 5 12:00:49 1999 Received: from darkwing.uoregon.edu (genghis@darkwing.uoregon.edu [128.223.142.13]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id MAA21384 for ; Tue, 5 Oct 1999 12:00:48 -0400 Received: from localhost (genghis@localhost) by darkwing.uoregon.edu (8.9.3/8.9.3) with SMTP id IAA22466 for ; Tue, 5 Oct 1999 08:52:32 -0700 (PDT) Date: Tue, 5 Oct 1999 08:52:32 -0700 (PDT) From: "Dale A. Braden" Reply-To: "Dale A. Braden" To: cclpost Subject: geom. opt. problem Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Dear CCL, In trying to optimize the geometry of CpMo(CO)3 (spin doublet, Cs symmetry) by DFT it arrived at a first order saddle point. Surprisingly, the vibrational mode with an imaginary frequency is totally symmetric, and corresponds to stretching of the ring CH bonds and the Mo-CO and CO bonds. When this kind of thing has happened before, I have just added the cartesian displacements of the normal mode with the imaginary frequency to the stationary geometry and reoptimized. In this case, it didn't work. If I view the stationary geometry, I see that the bond lengths and angles are not unusual (Mo-C = 2.0, CO = 1.15, CH = 1.08) and that if I add or subtract a larger displacement of the nuclei, then some of the bonds will certainly become unreasonably long or short (CH > 1.31 or < 0.83). I have tried displacing the geometry along both directions, and by different amounts, and calculating the force constants at the first point. I have also tried optimizing with some of the bond lengths constrained at first, and then relaxing the constraints. I also tried using tighter geometry convergence criteria. Finally, I tried reducing the symmetry to C1, switching from Gaussian98 to Jaguar (which also meant a change in basis and ECP), optimizing, switching back to Gaussian and then reoptimizing. In all cases, the same saddle point is obtained! There must be a better way. Any ideas? Best wishes to all, Dale Dale Braden Department of Chemistry University of Oregon Eugene, OR 97403-1253 genghis@darkwing.uoregon.edu From chemistry-request@server.ccl.net Tue Oct 5 13:20:39 1999 Received: from idun.phc.chalmers.se (idun.phc.chalmers.se [129.16.97.44]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id NAA21762 for ; Tue, 5 Oct 1999 13:20:38 -0400 Received: from fkrs2.phc.chalmers.se (fkrs2.phc.chalmers.se [129.16.97.48]) by idun.phc.chalmers.se (8.8.8/8.8.7) with ESMTP id SAA17243 for ; Tue, 5 Oct 1999 18:12:21 +0100 Received: (from svedung@localhost) by fkrs2.phc.chalmers.se (8.8.8/8.8.8) id TAA16434; Tue, 5 Oct 1999 19:12:20 +0200 Date: Tue, 5 Oct 1999 19:12:19 +0200 (MDT) From: Harald Svedung To: CHEMISTRY@ccl.net Subject: Scan Massage ? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Hi everyone! I'm trying to make as accurate calculations as possible on the interaction potentials between "atoms in molecules". I wish to make some BSSE-correction on some potential scans. I've tried the following for the colinear F2-F2 interaction: #RMP2/AUG-cc-pVTZ Scan Massage Test F-F F-F scan r2 0 1 F1 X1 F1 1. F2 F1 r1 X1 90. F3 F1 r2 X1 90. F2 180. X2 F3 1. F1 90. X1 180. F4 F3 r1 X2 90. F1 180. Variables: r2 1.10350222 6 0.1379377775 r1 1.40120372 3 Nuc 0.0 4 Nuc 0.0 as I want to use the basisfunctions on the second F2-molecule without the atoms to get a "maximum" correction for BSSE. Initially Gaussian seams to read this as taking away the second F2-molecule (output confirms 18 electrons), but when it comes to the scan it is confused regarding the numbering of the atoms and takes away not the second F2-molecule, but the F3 and X2 in the Z-matrix above. This results according to output in an odd number of electrons and thus a conflict with multiplicity. Is there a quick way arround this problem, some trivial keyword thing that I've missed or is this atom numbering missmatch in Gaussian a really unfortunate "feature"? All help is really welcome. yours :-) /Harald Harald Svedung (Ph.Lic.) phone: +46-31-7722816 Department of Chemistry fax: +46-31-167194 Physical Chemistry home phone: +46-31-240897, +46-709223206 Goeteborg University home e-mail: harald.svedung@svedung.pp.se SE-412 96 Goeteborg, Sweden www.che.chalmers.se/~svedung/ From chemistry-request@server.ccl.net Tue Oct 5 18:13:29 1999 Received: from nuhub.dac.neu.edu (nuhub.dac.neu.edu [129.10.1.6]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id SAA22849 for ; Tue, 5 Oct 1999 18:13:29 -0400 From: MARYJO@neu.edu Received: from neu.edu by neu.edu (PMDF V5.2-31 #39525) id <01JGS90FPJWG9M7R3C@neu.edu> for CHEMISTRY@CCL.NET; Tue, 5 Oct 1999 18:04:59 EST Date: Tue, 05 Oct 1999 18:04:59 -0500 (EST) Subject: vitamin B6 electronic structure To: CHEMISTRY@CCL.NET Message-id: <01JGS90FQCTU9M7R3C@neu.edu> X-VMS-To: CHEMISTRY@CCL.NET MIME-version: 1.0 Hello. I have a 1993 reference by T.L. Nero et al. (J Chem Soc Perkin 2, 431-436 (1993)) on the electronic structure of pyridoxal, a form of vitamin B6. Does anybody have anything more recent on B6 computation? Thanks, Mary Jo Ondrechen