Robustness of the I4 symmetry energy coefficient

In this paper we investigate the I4 symmetry energy coefficient [I=(N-Z)/A] extracted from a few popular mass models, and their corresponding databases improved, respectively, by the radial basis function (RBF) approach and the RBF with odd-even corrections. Our results show that the linear correlation between our resultant I4 symmetry energy coefficients (denoted by c4(V)) and the corresponding root-mean-square deviations from experimental masses of these theoretical databases is very robust. Interestingly, the extrapolated values of c4(V) using the above three versions of databases are consistent with each other.