From chemistry-request@ccl.net Fri May 3 00:18:14 1991 Date: Thu, 2 May 91 23:39:01 EDT From: Shi Yi Yue To: chemistry@ccl.net Subject: How to estimate d+ of C=O by varying its environment? Status: R Hi, I want to know how to estimate the partial charge (d+) as a function of the R group for the following system: d+ NH -- CH -- C = O | | C R where R = CH2-C=O, NH-CH2-C=O, CH2-CH2-C=O, CH2-CH2-CH2-C=O I am sure that there are a lot of studies have been done, so I will be very appreciated if you could point out the references about that problem, the solutions from ab initio, semi empirical, molecular mechanics, QSAR, etc.., all are welcome. If I receive enough answers, I'll post a summary. Thank you! ------------------ Shi-Yi Yue Ph.D. Biotechnology Research Institute | Phone: (514) 496-6338 6100 Royalmount Avenue | Fax: (514) 496-6232 Montreal Quebec Canada H4P 2R2 | E-mail: shiyi@bri.nrc.ca From chemistry-request@ccl.net Fri May 3 18:21:56 1991 From: breneman@quant.chem.rpi.edu Date: Fri, 3 May 91 17:39:54 EDT Status: R Folks, For computing electrostatic potential-derived charges from ab-initio wavefunctions generated by one of the Gaussian 86/88/90 packages, the CHELPG program is helpful. This program is a rotationally-invariant modification of the QCPE program CHELP by Chirlian and Francl. For a description of the CHELPG program and some results, see: Breneman, C. and Wiberg, K, J. Comput. Chem. 1990, 11, 361. The program source code is available for Unix and VMS via internet mail. Curt Breneman breneman@quant.chem.rpi.edu