Ab initio calculations and molecular mechanics (MM3) force field development for ammonium and protonated aliphatic amines
✍ Scribed by Liang, Guyan; Chen, Xiannong; Dustman, J. A.; Lewin, Anita H.; Bowen, J. Phillip
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 266 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0192-8651
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✦ Synopsis
The geometries and vibrational frequencies of 11 training molecules containing the ammonium ion moiety were calculated at the MP2r6-31qG U level of theory. Various torsional energy profiles were also calculated using this basis set. From those ab initio calculations, a molecular mechanics Ž . MM3 force field was developed using our Parameter Analysis and Refinement Ž . Toolkit System PARTS . Using this set of parameters, the MM3 force field was found to well reproduce the molecular geometries and vibrational spectra for the all training molecules. CPU time was reduced from days to seconds. The availability of this new force field dramatically increases the feasibility of the computer-assisted drug design involving ammonium and protonated amino groups.