WHIM descriptors of shape

WHIM descriptors are 3D structural descriptors obtained from the (x,y,z)-atomic coordinates of a molecular conformation of a chemical, and are used successfully in QSAR modelling. They are built in so as to capture relevant 3D information regarding different features of molecular structure: size, shape, symmetry and atom distribution. Different weights are used to obtain particular information for each set of descriptors. Recently, some doubts have been raised in the literature regarding the ability of Weighted Holistic Invariant Molecular (WHIM) descriptors of shape (the K non-directional WHIM descriptors) to describe the difference between linear and non-linear molecules. A data set of seventy aliphatic and aromatic chemicals of different shape (linear and branched congeners) has been studied here, and is represented by K descriptors (global nondirectional WHIM descriptors of shape) based on different weights. The K descriptors range from 0 for a spherical molecule to 1 for a perfectly linear molecule. The present study confirms the findings, already reported by the author, that the WHIM descriptors of shape (K) are unequivocally able to differentiate linear and non-linear molecules.