Fast approaches for molecular polarizability calculations.

Molecular polarizability of a molecule characterizes the capability of its electronic system to be distorted by the external field, and it plays an important role in modeling many molecular properties and biological activities. In this paper, a set of fast empirical models have been developed to predict molecular polarizability using two types of approaches. The first type of approaches is based on Slater's rules of calculating the effective atomic nuclear shielding constants. The best model (model 1A) of this category has achieved an average unsigned error (AUE), root-mean square error (RMSE), and average percent error (APE) of 2.23 au, 3.29 au, and 2.77%, respectively. The second type of model is based on an additive hypothesis of molecular polarizability. Five models have been constructed using different schemes of atom types. The best model that applies 14 atom types, model 2e, achieves AUE, RMSE, and APE of 0.99 au, 1.48 au, and 1.24%, respectively. This performance is much better than those of the models purely based upon chemical composition (model 2A and the Bosque and Sales model), for which errors are about 2-fold higher. It is expected that both model 1A and model 2E will have broad applications in QSAR and QSPR studies.