Returns: the Chemical shielding tensor in Maryland Notation

def maryland_values(self):
        """
        Returns: the Chemical shielding tensor in Maryland Notation
        """
        pas=self.principal_axis_system
        sigma_iso=pas.trace() / 3
        omega=np.diag(pas)[2] - np.diag(pas)[0]
        # There is a typo in equation 20 from Magn. Reson. Chem. 2008, 46, 582–598, the sign is wrong.
        # There correct order is presented in Solid State Nucl. Magn. Reson. 1993, 2, 285-288.
        kappa=3.0 * (np.diag(pas)[1] - sigma_iso) / omega
        return self.MarylandNotation(sigma_iso, omega, kappa)