List of 3D-MoRSE descriptors calculated by DRAGON

 

3D-MoRSE (3D-Molecule Representation of Structures based on Electron diffraction) descriptors are based on the idea of obtaining information from the 3D atomic coordinates by the transform used in electron diffraction studies for preparing theoretical scattering curves [J.H.Schuur, P.Selzer, J.Gasteiger, J. Am. Chem. Soc. 1996, 36, 334-344].

 

The following expression is used for 3D-MoRSE descriptor calculation:

 

 

where Morsw is the scattered electron intensity, w is an atomic property, rij are the interatomic distances and nAT is the number of atoms. The term s represents the scattering in various directions by a collection of nAT atoms.

 

In order to obtain uniform length descriptors, the intensity distribution is made discrete, calculating its value at a sequence of evenly distributed values; in particular, in DRAGON, it is assumed that s takes integer values in the range 0 – 31 (for s = 0 the scattering ratio is assumed equal to one).

 

32 3D-MoRSE descriptors are calculated for five different atomic properties w: the unweighted case (u), atomic mass (m), the van der Waals volume (v), the Sanderson atomic electronegativity (e) and, the atomic polarizability (p).