ORDER, DISORDER, AND GEOMETRICAL INFORMATION INDEXES OF MOLECULES

Structural features of various molecular systems with symmetry of poin t groups ranging from C-1 to the icosahedral symmetry are analyzed in the framework of the model suggested previously for the evaluation of order and disorder in the arrangement of atoms in a molecule based on the equation Q = 1 - P/3n (where Q is the index of order, and P is the number of independent coordinates needed to fix an n-atomic molecule in the Cartesian coordinate system). The Q value depends on various st ructural parameters of the molecule: the number of atoms in it, the sy mmetry, the dimensionality, and the number of structural degrees of fr eedom. The disorder index P/3n = 1 - Q correlates with Shannon's entro py of information, and Q correlates with negentropy or excess informat ion; this makes it possible to use P/3n as a new geometrical informati on molecular index that is obtained by a nonprobabilistic method. Anal ysis of the relationship between order and chaos in molecular systems, as well as of the specific order index q = Q/n, makes it possible to identify both general and specific features of molecules.