# pymatgen.io.cube module¶

Module for reading Gaussian cube files, which have become one of the standard file formats for volumetric data in quantum chemistry and solid state physics software packages (VASP being an exception).

Some basic info about cube files (abridged info from http://paulbourke.net/dataformats/cube/ by Paul Bourke)

The file consists of a header which includes the atom information and the size as well as orientation of the volumetric data. The first two lines of the header are comments. The third line has the number of atoms included in the file followed by the position of the origin of the volumetric data. The next three lines give the number of voxels along each axis (x, y, z) followed by the axis vector. The last section in the header is one line for each atom consisting of 5 numbers, the first is the atom number, the second is the charge, and the last three are the x,y,z coordinates of the atom center. The volumetric data is straightforward, one floating point number for each volumetric element.

Example In the following example the volumetric data is a 40 by 40 by 40 grid, each voxel is 0.283459 units wide and the volume is aligned with the coordinate axis. There are three atoms.

CPMD CUBE FILE. OUTER LOOP: X, MIDDLE LOOP: Y, INNER LOOP: Z

3 0.000000 0.000000 0.000000

40 0.283459 0.000000 0.000000 40 0.000000 0.283459 0.000000 40 0.000000 0.000000 0.283459

8 0.000000 5.570575 5.669178 5.593517 1 0.000000 5.562867 5.669178 7.428055 1 0.000000 7.340606 5.669178 5.111259

-0.25568E-04 0.59213E-05 0.81068E-05 0.10868E-04 0.11313E-04 0.35999E-05

: : : : : : : : : : : : : : : : : :

In this case there will be 40 x 40 x 40 floating point values

: : : : : : : : : : : : : : : : : :

class Cube(fname)[source]

Bases: object

Class to read Gaussian cube file formats for volumetric data.

Initialize the cube object and store the data as self.data :param fname: filename of the cube to read :type fname: str