Nonpairing like-nucleon valence residual interactions

Nonpairing like-nucleon residual interactions, δ${\mathit{V}}_{\mathit{n}\mathit{n}}$ and δ${\mathit{V}}_{\mathit{p}\mathit{p}}$, of the last two neutrons or protons are extracted from double differences of nuclear binding energies for all even-even nuclei. They are found to be weakly repulsive and, combined with analogous information on p-n interactions, provide an alternate way of demonstrating that the T=0 interaction is strongly attractive. Anomalies in δ${\mathit{V}}_{\mathit{n}\mathit{n}}$ and δ${\mathit{V}}_{\mathit{p}\mathit{p}}$ are shown to correlate with changes in core structure, and repulsive spikes for N=Z nuclei are interpreted in terms of shell-model calculations with realistic interactions.