An improved version of the steric difference method.

The steric difference (SD) method was developed to account for steric effects in the QSAR framework. The improved version (SD*) here reported takes into account the volume of different atoms, using some results recently obtained. The SD* method is applied to some concrete cases, and the obtained equations are compared with the results obtained from other methods. Finally, the physical significance of some steric parameters used in QSAR is discussed.