| Abstract: | Molecular mechanics (MM4) calculations on the heats of formation of aldehydes and ketones were carried out for a total of 59 compounds (10 aldehydes and 49 ketones). Optimization of the heat of formation parameters was obtained by a least squares fit to the experimentally known heats of formation. With the optimized MM4 heat of formation parameters, the MM4 calculated heats of formation showed significant improvement over those of MM3. The standard and weighted root mean square deviations for the MM4 values were 0.35 and 0.31 kcal mol?1, respectively, whereas for the MM3 values they were 0.42 and 0.39 kcal mol?1, respectively. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1476–1483, 2001 |
