Direct evaluation of the phase diagrams of dense multicomponent plasmas by integration of the Clapeyron equations

Accurate phase diagrams of multicomponent plasmas are required for the modeling dense stellar plasmas, such as those found in cores white dwarf stars and crusts neutron stars. Those have been computed using a variety standard techniques, which suffer from physical computational limitations. Here we present an efficient accurate method that overcomes drawbacks previously used approaches. In particular, finite-size effects avoided each is calculated separately; plasma electrons volume changes explicitly taken into account; arbitrary analytic fits to simulation data well particle insertions avoided. Furthermore, no simulations at ``uninteresting'' state conditions, i.e., away coexistence curves, required, improves efficiency technique. The consists adaptation so-called Gibbs-Duhem integration approach electron-ion where curve determined by direct numerical its underlying Clapeyron equation. thermodynamics properties coexisting phases evaluated separately Monte Carlo isobaric semigrand canonical ensemble ($\mathrm{NPT}\mathrm{\ensuremath{\Delta}}\ensuremath{\mu}$). We describe this Carlo-based method, including basic principles, our extension implementation. illustrate applicability benefits with calculation melting carbon-oxygen under conditions relevant provide implement new models. While work focuses on liquid-solid boundary two-component wider range systems boundaries within scope had until now only applied simple model neutral particles.