Density

From cclib

The Density class from cclib.method can be used to calculate the density matrix:

from cclib.parser import Gaussian
from cclib.method import Density

parser=Gaussian("myfile.out")
parser.parse()

d=Density(parser)
d.calculate()

After calculate() is called, the density attribute is available. It is simply a Numeric array with two axes, and follows the standard definition of the density matrix.