Self-consistent quantum Monte Carlo simulations of the structure of the liquid-vapor interface of a eutectic indium-gallium alloy

Abstract

We report the results of self-consistent quantum Monte Carlo simulations of the density distribution along the normal to the liquid-vapor interface, and the in-plane structure function, of the liquid-vapor interface of a eutectic binary alloy of indium and gallium (16.5% In) at 86 \ifmmode^\circ\else\textdegree\fi{}C. The density distribution along the normal to the interface exhibits layering, with a sensibly complete monolayer of In outermost in the interface. Our results are in good agreement with the experimental data of Regan et al. [Phys. Rev. B 55, 15874 (1997)]. We also report the results of self-consistent quantum Monte Carlo simulations of the structure of the liquid-vapor interfaces of In:Ga alloys with In concentrations greater than and less than the eutectic concentration. The In atoms segregate in the outermost layer of the interface as a sensibly complete monolayer when the bulk In concentration is 25% and as a partial monolayer when the bulk In concentration is 11%. In these cases, as well as for the eutectic alloy, there is some Ga well mixed with the In in the outermost layer of the stratified liquid-vapor interface. And for all alloy compositions studied the layer of the interface beneath the monolayer of segregated In is deficient in In relative to the bulk concentration; the bulk concentration of In is reached in the third layer of the liquid-vapor interface.