From chemistry-request@ccl.net Mon Jul 13 16:16:24 1992 Date: 13 Jul 1992 12:15:54 -0400 (EDT) From: "DR. DOUGLAS A. SMITH, UNIVERSITY OF TOLEDO" Subject: Re: Information about Tetrahedron Computer Methodology To: PDLMV@cellbio.stanford.EDU Status: R The journal Tetrahedron Computational Methodology died recently. Todd Wipke, the editor, posted the announcement to this mail exploder within the last few months. Doug Smith Assistant Professor of Chemistry The University of Toledo Toledo, OH 43606-3390 From chemistry-request@ccl.net Mon Jul 13 16:21:51 1992 Date: 13 Jul 92 10:02 LCL From: PA13808%UTKVM1.BITNET@OHSTVMA.ACS.OHIO-STATE.EDU Subject: BITNET mail follows To: CHEMISTRY@ccl.net Status: R GEOMETRY OF NITROGEN MOLECULES A number of reports of problems with calculating the geometry of amines using mol mech and semiempirical and small basis set ab initio calc have recently been aired on the network. I would like to refer interested workers to a paper by Boggs and NIU. J.of COMP CHEM. vol SIX pages 46-55 (1985) AB initio calc of amine out of plane Angles. This paper shows that very large basis sets with very siffuse s and p functions are needed on ALL atoms to solve this problem. I would infer from this that one should not be too upset if one gets incorrect results from cruder methods which are incapable of describing the " delicate balance between lone pair effects and delocalization" These methods do have severe limitations and this is clearly one of them. Something we have to learn to live with, despite the apparent early succsses of thirty years ago by Coulson, Hameka and Stephen Mason and others on the hybridization of amino compounds. On another topic The recently raised problem of why G90 would not give a planar (d3h)structure even though to all intents and purposes the trans state exists and could be gotten from a calc in C3v symm. It looks like another case of the need for extreme accuracy in inputting coordinates in this program. TRY using the NOSYMM option and see what it gives. This is a common problem formolecules with tetrahedral symmetry. Using bond dist and angles as input it is common for the program to end in errors because of apparent loss in symm.This problem was discussed a few months ago on the network. John E. Bloor(PA13808 at UTKVM1) From chemistry-request@ccl.net Mon Jul 13 19:00:40 1992 Date: 13 Jul 92 13:49:00 PST From: MAX VASQUEZ Subject: TCM - summary To: chemistry Status: RO Thanks to all that responded to my query. It appears that Tetrahedron Computer Methodology (TCM) no longer exists. A note appeared in this bulletin board about this (on May 4-th), which I somehow missed. For those interested a copy of the note follows (courtesy of Malcolm Cline at Tripos) and an address to contact for back issues follows the note. +++++++++++++++++++++ After completion of Volume 3, Tetrahedron Computer Methodology ceases publication. TCM-Online, the electronic on-line component also ceases and the on-line material (tables of contents) will be removed from the fileserver. The TCM BBS is now off-line. I want to thank the authors, libraries, and individual subscribers that supported TCM in words, disks, and actions. The idea behind TCM was that by publishing disks as well as paper, computer chemists could publish real experimentals that would bring reproducibility to the field. TCM published source code, executable code, data files, sample transcripts of computations, molecular structure files, and molecular animations, and actual document files on disk. It is now a collectors item. Back issues are available. I am curious to hear from subscribers your own analysis of what you found most interesting, what could be eliminated, etc.. I will appreciate such comments sent to wipke@secs.ucsc.edu. Anyone interested in obtaining back issues should contact Pergamon Press directly, not me. -Todd Wipke Editor-in-Chief +++++++++++++++++++++++ The address for back issues is: "Pergamon Press, Inc., Fairview Park, Elmsford, New York, 10523 USA" ++++++++++++++++++++++++++ Thanks to all again, Max Vasquez