def distance(self, xyz=(0.00, 0.00, 0.00)):
        """Computes Euclidean distance between atoms in
            self.df and a 3D point.

        Parameters
        ----------
        xyz : tuple (0.00, 0.00, 0.00)
            X, Y, and Z coordinate of the reference center for the distance
            computation

        Returns
        ---------
        pandas.Series : Pandas Series object containing the Euclidean
            distance between the atoms in the atom section and `xyz`.

        """
        return np.sqrt(np.sum(self.df[['x', 'y', 'z']]
                       .subtract(xyz, axis=1)**2, axis=1))
Computes Euclidean distance between atoms in
            self.df and a 3D point.

        Parameters
        ----------
        xyz : tuple (0.00, 0.00, 0.00)
            X, Y, and Z coordinate of the reference center for the distance
            computation

        Returns
        ---------
        pandas.Series : Pandas Series object containing the Euclidean
            distance between the atoms in the atom section and `xyz`.