As far as I know the utility used in Gaussian 09 program for drawing charge density or potential is named CUBEGEN. From its name you can that the data is generated in rectangular coordinates (x,y,z). However Gaussian 09 program offer to read the calculated data using fortran subroutines in a given format. The remaining task is to use rectangular to spherical coordinates transformation to get radial density and spherically averaged potential. For more information see: