def METHOD_NAME(self):
    """
    An array containing charge density data.
    Returns
    -------
    `~astropy.units.Quantity`
    """
    path = f"data/{self.subname}/fields/rho"
    if path in self.h5:
        units = _fetch_units(self.h5[path].attrs["unitDimension"])
        return np.array(self.h5[path]) * units
    else:
        raise AttributeError("No charge density data available in HDF5 file")