Structural changes in the Lennard-Jones supercooled liquid and ideal glass: An improved integral equation for the replica method

Framing the glass formation within standard statistical mechanics is an outstanding problem of condensed matter theory. To add insight, we investigate the structural properties of the Lennard-Jones fluid in the very-low temperature regime by using a replicated version of the refined HMSA theory of the liquid state combined with an appropriate split of the pair potential [Bomont and Bretonnet, J. Chem. Phys.114, 4141 (2026) 0021-9606 10.1063/1.1344610]. Our scheme allows one to reach an unprecedented low-temperature domain within both the supercooled liquid and the ideal-glass phase. Therein, a density-dependent temperature is identified, whereupon the radial distribution function experiences clear-cut structural changes, insofar as an additional peak develops in between the main and the second peaks. Such a structural feature points to a local structure of the Lennard-Jones ideal glass with an fcc-like short-range order, in the absence of any long-range order.