parameter WS a$_{v}$ (MeV) − 15 . 5841 a$_{s}$ (MeV) 18.2359 a$_{c}$ (MeV) 0.7173 c$_{sym}$ (MeV) 29.2876 κ 1.4492 a$_{pair}$ (MeV) − 5 . 5108 g$_{1}$ 0.00862 g$_{2}$ − 0 . 4730 c$_{1}$ 0.7274 V$_{0}$ (MeV) − 47 . 4784 r$_{0}$ (fm) 1.3840 a (fm) 0.7842 λ$_{0}$ 26.3163 TABLE I: Model parameters of the mass formula. fitting the calculated results. The obtained values of V$_{s}$ are 17.0 and 26.9 MeV with SLy4 [23] and SkM* [15] force, respectively. In [24], the authors found that the experimental Fermi energies of a number of magic nuclei can be well described with a value of 23.2 MeV for V$_{s}$ . The a$_{sym}$ in this work has a value of about 23 ∼ 24 MeV for heavy nuclei which is roughly comparable to the obtained values of V$_{s}$ . In the first round of searching for the optimal parameters of the proposed mass formula, we treat V$_{s}$ as a free parameter and find that the obtained value of V$_{s}$ is very close to that of a$_{sym}$ . So we empirically set and assume V$_{s}$ ≈ a$_{sym}$ in the improved mass formula for simplification. E. Model Parameters From the above discussions, one can see that the macroscopic and microscopic parts in the proposed mass formula are closely connected to each other through the coefficient a$_{sym}$ of the symmetry energy and other isospin dependent model parameters. The number of model parameters is considerably reduced compared with the finite range droplet model (FRDM) in which the number of parameters is about 31 [1]. Here, we have 13 independent parameters a$_{v}$ , 11