Wigner term generated by isovector p-n pairing

The linear term proportional to |N - Z| in the nuclear symmetry energy (Wigner energy) is obtained in a model that uses isovector pairing on single particle levels from a deformed potential combined with a T super(2) interaction. The pairing correlations are calculated by numerical diagonalization of the pairing Hamiltonian acting on the six or seven levels nearest the N = Z Fermi surface. The experimental binding energies of nuclei with N [approx =] Z are well reproduced. The Wigner energy emerges as a consequence of restoring isospin symmetry.