Script for creating an NCI surface as a JVXL compressed file from a (Gaussian) cube of total electron density

A Script to generate a  NCI surface from a Gaussian  Cube file, and to write the result as two files, a  .xyz coordinate file and a  .jvxl isosurface file.

See  E. R. Johnson, S. Keinan, P. Mori-Sánchez, J. Contreras-García, A. J. Cohen and W.  Yang, J. Am. Chem. Soc., 2010, 132, 6498–6506. doi: 10.1021/ja100936w  for details of the  theoretical procedure.

The NCI procedure was implemented in Jmol by Bob Hanson.