The repulsive interaction between proton particles and neutron holes in the (spin-isospin) channel gives rise to a giant charge-exchange resonance in all nuclei with excess neutrons. The centroid of the resonance (which typically has a width of 5-10 MeV) can be roughly parameterized by the simple formula , where is the centroid of the Fermi resonance [44]. This formula, however, captures only average behavior; individual cases depend on single-particle structure, and in particular the spin-orbit splitting.
The ability to model GT resonances is crucial for predictions
of nuclear
decay. Just as the low-lying E1 strength is
depleted by the giant dipole resonance, so the low-lying GT
strength, responsible for
decay, is affected by the GT
resonance. Since one of our future goals is an improved calculation
of -decay rates in nuclei along the r-process path, it is
important to develop a reliable description of the GT giant
resonance.