An improved nuclear mass formula: WS3

We introduce a global nuclear mass formula which is based on the macroscopic-microscopic method, the Skyrme energy-density functional and the isospin symmetry in nuclear physics. The rms deviation with respect to 2149 known nuclear masses falls to 336 keV, and the rms deviations from 1988 neutron separation energies and \alpha-decay energies of 46 super-heavy nuclei are significantly reduced to 286 and 248 keV, respectively. The predictive power of the mass formula for describing new measured masses in GSI and those in AME2011 is excellent. In addition, we introduce an efficient and powerful systematic method, radial basis function approach, for further improving the accuracy and predictive power of global nuclear mass models.