Returns the geometry with the minimum continuous symmetry measure of this ChemicalEnvironments
        :return: tuple (symbol, csm) with symbol being the geometry with the minimum continuous symmetry measure and
        csm being the continuous symmetry measure associted to it
        :raise: ValueError if no coordination geometry is found in this ChemicalEnvironments object

def minimum_geometry(self, symmetry_measure_type=None, max_csm=None):
        """
        Returns the geometry with the minimum continuous symmetry measure of this ChemicalEnvironments
        :return: tuple (symbol, csm) with symbol being the geometry with the minimum continuous symmetry measure and
        csm being the continuous symmetry measure associted to it
        :raise: ValueError if no coordination geometry is found in this ChemicalEnvironments object
        """
        if len(self.coord_geoms) == 0:
            return None
        cglist = [cg for cg in self.coord_geoms]
        if symmetry_measure_type is None:
            csms = np.array([self.coord_geoms[cg]['other_symmetry_measures']['csm_wcs_ctwcc'] for cg in cglist])
        else:
            csms = np.array([self.coord_geoms[cg]['other_symmetry_measures'][symmetry_measure_type] for cg in cglist])
        csmlist = [self.coord_geoms[cg] for cg in cglist]
        imin = np.argmin(csms)
        if max_csm is not None:
            if csmlist[imin] > max_csm:
                return None
        return cglist[imin], csmlist[imin]