  We propose a semi-empirical nuclear mass formula based on the
macroscopic-microscopic method in which the isospin and mass dependence of
model parameters are investigated with the Skyrme energy density functional.
The number of model parameters is considerably reduced compared with the finite
range droplet model. The rms deviation with respect to 2149 measured nuclear
masses is reduced by 21%, falls to 0.516 MeV. The new magic number N=16 in
light neutron-rich nuclei and the shape coexistence phenomena for some nuclei
have been examined with the model. The shell corrections of super-heavy nuclei
are also predicted.
