Isospin-dependent phase diagram of nuclear matter

Abstract

In this article we obtain the phase diagram of nuclear matter extending it from the traditional two-dimensional density-temperature plane to three-dimensional space of density, temperature, and isospin asymmetry. We identify the liquid-gas coexistence region by means of Maxwell constructions over pressure-volume isotherms. Such pressure-density equations of state were constructed from data obtained from interpolating results from molecular dynamics simulations of infinite nuclear systems in the liquid phase those of Fermi gases at low (sub-saturation) densities. The molecular dynamics results were used to obtain the energy per nucleon and pressure for systems with densities and temperatures in the ranges ρ=0.01 to 0.2 fm−3, T between 1 and 15 MeV, and with isospin content of x = Z/A = 0.3, 0.35, 0.4, 0.45 and 0.5. The results indicate that symmetric and asymmetric matter are self-bound and show a coexistence region that extends, approximately, to densities of up to ρ0/2, temperatures of up to 16 MeV, and down to proton fractions of 13%.