Calculation of heats of sublimation and solid phase heats of formation

Abstract

We show that the heats of sublimation of 34 organic compounds of various types can be represented analytically in terms of the surface areas of the molecules and the positive and negative variances of their surface electrostatic potentials. These properties are computed at the ab initio HF/STO-5G*//HF/STO-3G* level. The relationship between the calculated and experimental values for our data base has a correlation coefficient of 0·95 and standard deviation of 2·5 kcal mol-1. Heats of sublimation obtained by this approach are combined with gas phase heats of formation computed by a density functional procedure (developed earlier) to yield solid phase heats of formation. The latter, for five test compounds, have an average error of 2·8 kcal mol-1.