MORPHY, a program for an automated “atoms in molecules” analysis Original Research Article

The operating manual for a structured FORTAN 77 program called MORPHY is presented. This code performs an automated topological analysis of a molecular electron density and its Laplacian. The program is written in a stylistically homogeneous, transparant and modular manner. The input is compact but flexible and allows for multiple jobs in one deck. The output is detailed and has an attractive lay-out. Critical points in the charge density and its Laplacian can be located in a robust and economic way and are displayed via an external on-line visualisation package. The gradient vector field of the charge density can be traced with great accuracy, planar contour, relief and one-dimensional line plots of many scalar properties can be generated. Non-bonded radii are calculated and analytical expressions for interatomic surfaces are computed (with error estimates) and plotted. MORPHY is interfaced with the AIMPAC suite of programs. The capabilities of the program are illustrated with two test runs and five selected figures.