Analysis of Structural Change across the Liquid-Liquid Transition and the Widom Line in Supercooled Stillinger-Weber Silicon

We consider the changes in the structure of supercooledStillinger-Webersilicon at pressures at which the studied range of temperatures traversesthe liquid-liquid transition or the "Widom line"(at which the isothermal compressibility or the specific heat exhibitsa maximum). In addition to the conventional characterizations in termsof the pair-correlation function and bond orientational order, weanalyze the statistics of rings in the bond network as well as thestatistics of clusters of low density liquid (LDL)- and high densityliquid (HDL)-like atoms. We investigate the nature of the change inthese structural characterizations when the liquid-liquid transitionline or the Widom line is crossed. We find that the isobaric temperaturevariation of these structural features reveals clear indications ofmaximal structural heterogeneity or frustration upon crossing theliquid-liquid transition or the Widom line, as in the caseof water, but with some differences in detail, which we discuss.