Evolution of short range order in Ar: Liquid to glass and solid transitions–A computational study

Abstract

Evolution of short range order in Ar:Liquid to glass and solid transitions-A computational study The evolution of the short range order (SRO) as a function of temperature in a Lennard-Jones model liquid with Ar parameters was determined and juxtaposed with thermodynamic and kinetic properties obtained as the liquid was cooled (heated) and transformed between crystalline solid or glassy states and an undercooled liquid. The Lennard-Jones system was studied by non-equilibrium molecular dynamics simulations of large supercells (approximately 20000 atoms) rapidly cooled or heated at selected quenching rates and at constant pressure. The liquid to solid transition was identified by discontinuities in the atomic volume and molar enthalpy; the glass transition temperature range was identified from the temperature dependence of the self-diffusion. The SRO was studied within the quasi-crystalline model (QCM) framework and compared with the Steinhardt bond order parameters. Within the QCM it was found that the SRO evolves from a bcc-like order in the liquid through a bct-like short range order (c/a=1.2) in the supercooled liquid which persists into the glass and finally to a fcc-like ordering in the crystalline solid.

DeepIce: A Deep Neural Network Approach To Identify Ice and Water Molecules

“…Identifying the local arrangements of molecules within condensed phases is a key task in computer simulations aimed at studying phenomena such as phase transitions, [1][2][3][4][5] nucleation, [6][7][8] crystal growth 9,10 and defect formation. 11,12 Ice surfaces, which strongly influence the macroscopic properties of ice, are an interesting example of multi-phase systems.…”

“…Identifying the local arrangements of molecules within condensed phases is a key task in computer simulations aimed at studying phenomena such as phase transitions, − nucleation, − crystal growth, , and defect formation. , Ice surfaces, which strongly influence the macroscopic properties of ice, are an interesting example of multiphase systems . Over a significant temperature range, ice surfaces premelt and develop a quasi-liquid layer (QLL) which mediates crystal growth and chemical reactions. − Computational studies of molecules at interfaces, including at the environmentally significant ice-QLL interface, rely on a precise and accurate method to distinguish between the local environment of molecules.…”

Is icosahedral short-range order presented in supercooled transition metals?

“…As can be seen from the figure, supercooled nickel melts do not contain any ideal or distorted clusters with icosahedral (fivefold) symmetry, as indicated earlier in [27,[30][31][32][33]. It should be noted, no evidence of an icosahedral short-range order has been found for a number of disordered systems [47,48]. So, for example, a small angle neutron scattering experiments on the liquid rubidium did not reveal signatures of the supposed icosahedral clusters [47].…”