Determining atom-centered monopoles from molecular electrostatic potentials. The need for high sampling density in formamide conformational analysis
Article first published online: 7 SEP 2004
Copyright © 1990 John Wiley & Sons, Inc.
Journal of Computational Chemistry
Volume 11, Issue 3, pages 361–373, April 1990
How to Cite
Breneman, C. M. and Wiberg, K. B. (1990), Determining atom-centered monopoles from molecular electrostatic potentials. The need for high sampling density in formamide conformational analysis. J. Comput. Chem., 11: 361–373. doi: 10.1002/jcc.540110311
- Issue published online: 7 SEP 2004
- Article first published online: 7 SEP 2004
- Manuscript Accepted: 12 OCT 1989
- Manuscript Received: 12 JUN 1989
An improved method for computing potential-derived charges is described which is based upon the CHELP program available from QCPE.1 This approach (CHELPG) is shown to be considerably less dependent upon molecular orientation than the original CHELP program. In the second part of this work, the CHELPG point selection algorithm was used to analyze the changes in the potential-derived charges in formamide during rotation about the CN bond. In order to achieve a level of rotational invariance less than 10% of the magnitude of the electronic effects studied, an equally-spaced array of points 0.3 Å apart was required. Points found to be greater than 2.8 Å from any nucleus were eliminated, along with all points contained within the defined VDW distances from each of the atoms. The results are compared to those obtained by using CHELP. Even when large numbers of points (ca. 3000) were sampled using the CHELP selection routine, the results did not indicate a satisfactory level of rotatational invariance. On the basis of these results, the original CHELP program was found to be inadequate for analyzing internal rotations.