List of Burden eigenvalue descriptors calculated by DRAGON

 

These molecular descriptors were originally proposed to address searching for chemical similarity/diversity on large data bases [R.S. Pearlman, K.M. Smith, Novel Software Tools for Chemical Diversity in 3D QSAR in Drug Design - Vol. 2, H. Kubinyi, G. Folkers, Y.C. Martin (Eds.), Kluwer/ESCOM, Dordrecht (The Netherlands), pp. 339-353, 1998] and are based on a significant extension of the Burden approach [F.R. Burden, J.Chem.Inf.Comput.Sci. 1989, 29, 225-227]. They are derived for a hydrogen-included molecular graph and calculated from the Burden matrix, which is a modified adjacency matrix defined as the following: the diagonal elements are atomic properties; the off-diagonal elements corresponding to pairs of bonded atoms are the square roots of conventional bond order; all other matrix elements are set at 0.001.

 

DRAGON calculates 4 different Burden matrices whose diagonal elements correspond to 1) atomic masses (m), 2) atomic van der Waals volumes (v), 3) atomic Sanderson electronegativities (e), and 4) atomic polarizabilities (p).

 

For each of these matrices the Burden descriptors are calculated as an ordered sequence of the highest and lowest eigenvalues, which have been demonstrated to reflect relevant aspects of molecular structure, and are therefore useful for similarity searching.

 

DRAGON provides the first 8 highest eigenvalues BEHwk and the first 8 lowest eigenvalues BELwk (absolute values) for each matrix, w referring to the atomic property and k to the eigenvalue rank.