The neutron-proton (n-p) isovector pairing effect on the nuclear moment of inertia has been studied within the framework of the BCS approximation. An analytical expression of the moment of inertia, that explicitly depends upon the n-p pairing, has been established using the Inglis cranking model. The model was first tested numerically for nuclei such as N = Z and whose experimental values of the moment of inertia are known (i.e. such as 16 ≤ Z ≤ 40). It has been shown that the n-p pairing effect is non-negligible and clearly improves the theoretical predictions when compared to those of the pairing between like particles. Secondly, predictions have been established for even-even proton-rich rare-earth nuclei. It has been shown that the n-p pairing effect is non-negligible when N = Z and rapidly decreases with increasing values of (N-Z).

Expressions of temperature-dependent perpendicular (ℑ⊥) and parallel (ℑ‖) moments of inertia, including isovector pairing effects, have been established using the cranking method. They are derived from recently proposed temperature-dependent gap equations. The obtained expressions generalize the conventional finite-temperature BCS (FTBCS) ones. Numerical calculations have been carried out within the framework of the schematic Richardson model as well as for nuclei such as N = Z, using the single-particle energies and eigenstates of a deformed Woods–Saxon mean-field. ℑ⊥ and ℑ‖ have been studied as a function of the temperature. It has been shown that the isovector pairing effect on both the perpendicular and parallel moments of inertia is non-negligible at finite temperature. These correlations must thus be taking into account in studies of warm rotating nuclei in the N ≃ Z region.

The influence of the isovector neutron–proton (np) pairing effect on nuclear statistical quantities is studied in N ≈ Z even–even systems. Expressions of the energy, the entropy, and the heat capacity are established using a recently proposed temperature-dependent isovector pairing gap equations. They generalize the conventional finite temperature BCS (FTBCS) ones. The model is first numerically tested using the schematic one-level model. As a second step, realistic cases are considered using the single-particle energies of a deformed Woods–Saxon mean-field. It is shown that: (i) the gap parameter Δnp(T) behaves like Δtt(T), t = n, p, in the conventional FTBCS model and the critical temperature value Tcnp is such as Tcnp<Tcp<Tcn; (ii) the behavior of Δtt(T), t = n, p in the present model is different from that of the FTBCS one. This fact leads to a systematic discrepancy between the predictions of both models in the Tcnp<T<Tcn region for all studied statistical quantities; and (iii) in the 0≤T≤Tcnp region, the np pairing effect on the energy is a lowering of about 1%, on average, for all considered nuclei. Dealing with the entropy and the heat capacity, the np pairing effect appears only if the Tcnp value is sufficiently important.