Isostructural solid-solid transitions in binary asymmetrical hard sphere system: Based on solvent-mediated potential

Size dependence is imparted onto a modified bridge functional, adopted for a recently proposed semi-analytical hard sphere reference system theory for calculation of solvent-mediated potential (SMP). The SMP for two large hard sphere particles immersed in a small hard sphere solvent bath predicted by the present improved version is in satisfactory agreement with the prediction from a theoretically based fitting formula. Isostructural solid-solid transitions in the binary asymmetrical hard sphere system are investigated based on a single-component macrofluid approximation combined with the improved version. It is found that the isostructural solid-solid transition appears when size asymmetry increases. The limiting asymmetry size ratio is near 1/8. As the size asymmetry increases, critical density for both large and small hard sphere components for the fcc isostructural solid-solid transition increases and decreases, respectively.