From bewilson@Kodak.COM Fri Nov 13 08:43:48 1992 Date: Fri, 13 Nov 92 13:43:48 -0500 Message-Id: <9211131844.AA12060@Kodak.COM> From: bewilson@Kodak.COM (Bruce E. Wilson, ECCR-PA, B95-A, X8886 (bewilson@kodak.com)) To: "chemistry@ccl.net"@Kodak.COM Subject: modelling chair-boat transitions in cyclohexanes I'm interested in modelling the transitions between chair and boat conformations of (e.g.) 1,4-disubstituted cyclohexanes. In particular, I am interested in studying the effects of different subsituents on the barrier energy between the conformers. I would also be interested in being able to compare the width of the well--i.e. the small scale motional conformational freedom avaialable to the molecule. The concept I'm looking at would be to use MOPAC and systematically vary two (adjacent) dihedral angles in the ring, allowing the rest of the molecule to relax. From that "phi-psi" plot, I ought to be able to extract some approximate information on the height of the transformation barrier and whether or not a given substituent has raised or lowered that barrier relative to a reference compound. Does anyone have any particular thoughts in this regard and/or some literature references on this particular subject? Thanks. ----------------- | ___ ________ | Bruce E. Wilson | | / / | | Senior Research Chemist | | / / | | Eastman Chemical Company | |< < K O D A K| | P. O. Box 1972, Building 150 | | \ \ | | Kingsport, TN 37662-5150 | |__\ \________| | voice: 615/229-8886 FAX: 615/229-4558 | | INTERNET: bewilson@kodak.com ----------------- From ken@tcrystal.glasgow.ac.uk Sat Nov 14 13:06:39 1992 From: Kenneth Shankland Date: Sat, 14 Nov 92 13:06:39 GMT Message-Id: <29974.9211141306@samurai.tcrystal.tcrystal.glasgow.ac.uk> To: CHEMISTRY@ccl.net Subject: Crystal Morphology Drawing Software As part of an update to our Mithril direct methods package, we are about to embark on writing some code to sketch crystals given information like crystal axis lengths and angles, point group symmetry etc. This is largely to facilitate the use of abs. correction code. The program will display under X-windows and will output PostScript. I would be grateful if anyone could point us in the direction of some public domain code which does this type of sketching on any device (plotter, IBM-PC type display etc..) before we re-invent the wheel. Thanks in anticipation, Kenneth Shankland Crystallography Lab 358 Chemistry Department The University Glasgow, Scotland ken@uk.ac.glasgow.tcrystal