From pc1@pctc.chemie.uni-erlangen.de Wed Dec 23 14:05:23 1992 Message-Id: <9212231205.AA14432@pc1.chemie.uni-erlangen.de> To: chemistry@ccl.net Subject: Utility mpp - Version 1.0 Date: Wed, 23 Dec 92 13:05:23 +0100 From: Inst.f.Phys.Chem. I Dear netters, First let me wish everyone a merry christmas and a happy new year. Second I would like to present a small utility to the net, that might be usefull to everyone who works with mopac. ======================================== Mopac - Preprocessor (mpp) Version 1.0 ======================================== Molecular geometries can be defined in several ways, for example by using cartesian coordinates or by using internal coordinates. The last possibilty is used in the case of the well-known Z-matrix. One of the major disadvantages of using the conventional Z-matrix as an input for Mopac-calculations is the difficulty in keeping track of the numbering of used atoms. This can get quite tricky in the case of very large molecules. Another problem frequently encountered in the construction of a Z-matrix is, if one wants to substitute the functional groups of a molecule by other substituents. The program mpp enables the construction of a Z-matrix in a different and new way. The molecule is splitted in smaller fragments, so that a Z-matrix can be constructed without much efforts, and subsequently defining the location of a fragment relative to another. The benefits of the above method are: o The construction of a Z-matrix, even for larger molecules, is much easier without having to resort to computer programs like PC-model. o Substituting fragments of a molecule with different fragments, does not require a recalculation of the referenced atom numbers. o By using an archive of fragments, it is not necessary to reconstruct frequently used fragments again and again. (e.g. Methyl- or phenylgroups) Another case where the new method is useful, is when one wants to look at the interaction of two or more molecules. I you want to use this program let me know by E-Mail and I will send it to you. Peter Gedeck Inst.f.Phys.Chem. I Egerlandstrasse 3 8520 Erlangen Germany gedeck@pctc.chemie.uni-erlangen.de ++49-9131-85 7335