Theoretical and computational study on structure, dynamics, and configurational entropy correlation in gold-silicon liquid

The structure–property relationship of partially ordered systems poses a different type of open problem for both theoretical and experimental condensed matter researchers. Configurational entropy is an important thermodynamic property that characterizes the glass transition ability of binary liquid alloys. Recently, various experimental and computational approaches have been reported to investigate the configurational entropy in liquids; however, a well-established theoretical definition is still lacking. In this study, the configurational entropy of binary melts has been computed using their pair correlation functions. We determine three partial structure factors that govern the total structure factor S(k) in liquid AuySix alloys at different compositions and temperatures. Fourier inversion of partial and total structure factors gives partial pair correlation functions and radial distribution functions g(r) of AuySix melts, respectively. The computed values of S(k) and g(r) are in excellent agreement with available experimental results. The present model calculation of S(k) for eutectic AuySix melts (x = 19 at. % Si) shows better agreement with the experimental values than the molecular dynamics simulation data. Furthermore, we determine the friction coefficients experienced by constituent particles in the attractive and repulsive regions of the square-well (SW) potential function and employed in Einstein's equation to determine the self- and mutual diffusion coefficients as a function of composition and temperature. The diffusivity of Au and the mutual diffusion coefficient of the alloy are also in good agreement with experimental values compared to molecular dynamics data at its eutectic composition, which confirms the applicability of the SW model for such alloys.