The nuclear binding energy is defined as the energy required to break up a given nucleus into its constituent parts of $N$ neutrons and $Z$ protons. In terms of the atomic masses $M(N, Z)$ the binding energy is defined by $$BE(N, Z) = ZM_H c^2 + Nm_n c^2 - M(N, Z)c^2 ,$$ where $M_H$ is the mass of the hydrogen atom and $m_n$ is the mass of the neutron. In terms of the mass excess the binding energy is given by $$BE(N, Z) = Z\Delta_H c^2 + N\Delta_n c^2 -\Delta(N, Z)c^2 ,$$ where $\Delta_H c^2 = 7.2890$ MeV and $\Delta_n c^2 = 8.0713$ MeV.