Graphics visualization of molecular surfaces.

An algorithm for generation and visualization of a variety of molecular surfaces is described. The algorithm employs center-of-mass or nuclei-centered spherical polar coordinate systems. In the present work, surfaces based on two fundamental molecular scalar fields, viz., the molecular electron density (MED) and the molecular electrostatic potential (MESP), are considered. Four such surfaces are presented: a constant MED surface with rho = 0.002 au; a minimal MESP anionic surface defined recently by Gadre et al.; a molecular covalency surface with a constant MESP value chi (chi being the Mulliken electronegativity value); and the van der Waals (vdW) surface. The MESP is superposed as a "texture" on the first and last surfaces. The color graphics visualization of these surfaces is implemented on a Silicon Graphics IRIS 4D/20 workstation. Several illustrative examples are presented.