def calculate_centre_of_mass(self):
self.centre_of_mass = center_of_mass(self.elements, self.coordinates)<EOL>self.properties['<STR_LIT>'] = self.centre_of_mass<EOL>return self.centre_of_mass<EOL>
Return the xyz coordinates of the centre of mass of a molecule.

Returns
-------
:class:`numpy.array`
    The centre of mass of the molecule.