Computational investigation of structure, dynamics and nucleation kinetics of a family of modified Stillinger-Weber model fluids in bulk and free-standing films

MELISA M GIANETTI; AMIR HAJI AKBARI BALOU; MA. PAULA LONGINOTTI; PABLO G DEBENEDETTI

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2016 vol. 18 p. 4102 - 4111

1463-9076

In recent years, computer simulations have found increasingly widespread use as powerful tools forstudying phase transitions in wide variety of systems. In the particular and very important case ofaqueous systems, the commonly used force-fields tend to offer quite different predictions with respectto a wide range of thermodynamic and kinetic properties, including the ease of ice nucleation, thepropensity to freeze at a vapor?liquid interface, and the existence of a liquid?liquid phase transition. It isthus of fundamental and practical interest to understand how different features of a given water modelaffect its thermodynamic and kinetic properties. In this work, we use the forward-flux samplingtechnique to study the crystallization kinetics of a family of modified Stillinger-Weber (SW) potentialswith energy (e) and length (s) scales taken from the monoatomic water (mW) model, but with differenttetrahedrality parameters (l). By increasing l from 21 to 24, we observe the nucleation rate increases by48 orders of magnitude at a supercooling of z = T/Tm = 0.845. Using classical nucleation theory, we areable to demonstrate that this change can largely be accounted for by the increase in |Dm|, the thermodynamicdriving force. We also perform rate calculations in freestanding thin films of the supercooledliquid, and observe a crossover from surface-enhanced crystallization at l = 21 to bulk-dominatedcrystallization for l Z 22.