Regular Article

The role of local bond-order at crystallization in a simple supercooled liquid

DNRF Centre “Glass and Time”, IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark

^a e-mail: st@ruc.dk

Received: 20 July 2020
Received in final form: 7 September 2020
Accepted: 9 September 2020
Published online: 4 November 2020

Abstract

Large scale Molecular Dynamics simulations of 65 systems with N = 80 000 Lennard–Jones particles at two different supercooled liquid state points reveal, that the supercooled states contain spatially heterogeneous distributed subdomains of particles with significant higher bond-order than the mean bond-order in the supercooled liquid. The onset of the crystallization starts in such an area with relatively high six-fold bond-order for a supercooled state, but low bond-order for a fcc crystal state, and the crystallization is initiated by a nucleus where all particles in the critical nucleus have a significant lower bond-order than in a fcc crystal. The critical nucleus of N ≈ 70 particles is surrounded by many hundreds of particles with relatively high supercooled liquid bond-order and many of these particles are aligned with the crystal ordered particles in the critical nucleus. The crystallizations are very fast and supported by a fast growth of the supercooled areas with relative high liquid bond-order. The crystallizations are to fcc crystals, but a significant part of the crystallizations exhibit five-fold arrangements of polycrystalline subdomains mainly with fcc crystal order and sign of hcp crystallites.