Ice nucleation on carbon surface supports the classical theory for heterogeneous nucleation

Abstract

The prevalence of heterogeneous nucleation in nature was explained qualitatively by the classical theory for heterogeneous nucleation established over more than 60 years ago, but the quantitative validity and the key conclusions of the theory have remained unconfirmed. Employing the forward flux sampling method and the coarse-grained water model mW, we explicitly computed the heterogeneous ice nucleation rates in the supercooled water on a graphitic surface at various temperatures. The independently calculated ice nucleation rates were found to fit well according to the classical theory for heterogeneous nucleation. The fitting procedure further yields the estimate of the potency factor which measures the ratio of the heterogeneous nucleation barrier to the homogeneous nucleation barrier. Remarkably, the estimated potency factor agrees quantitatively with the volumetric ratio of the critical nuclei between the heterogeneous and homogeneous nucleation.Our numerical study thus provides a strong support to the quantitative power of the theory, and allows understanding ice nucleation behaviors under the most relevant freezing conditions.

Enhanced heterogeneous ice nucleation by special surface geometry

“…When filled with water inside, this tetrahedral pyramid wedge is found to lead to spontaneous ice crystallization within 2 ns in direct molecular dynamics (MD) simulation at 240 K. In fact, the nucleation efficiency for tetrahedral pyramid is so high that one has to raise the temperature significantly, to explicitly compute its ice nucleation rate by FFS method. At 250 K, the calculated nucleation rate 9.6 × 10 30  m −3  s −1 for tetrahedral pyramid exceeds those on flat graphene and in bulk water at the same temperature (estimated on the basis of CNT22) by nearly 30 and 90 orders of magnitude, respectively.…”

Thermodynamically driven assemblies and liquid–liquid phase separations in biology

“…This question has fascinated statistical physicists and biophysicists for decades [182,267,268], and has been recently investigated for simpler hydrophobic models using extensive molecular simulations and path sampling techniques [269][270][271][272][273]. Nevertheless, the precise kinetics and mechanism of hydrophobic assembly in biological systems is far from fully understood, and considering the power of state-of-the-art advanced sampling techniques in elucidating the mechanism of other rare events such as crystallization [274][275][276][277][278][279][280], they can be very useful in understanding the hydrophobic effect. IDPs are excellent systems in this regard, as they tend to phase separate and assemble despite having low hydrophobic-ity, and understanding the molecular origins of such behavior is critical to unraveling the longstanding question of hydrophobicity and biological assembly.…”

The Many Faces of Heterogeneous Ice Nucleation: Interplay Between Surface Morphology and Hydrophobicity

“…Recently all-atom simulations of homogeneous ice nucleation have been performed 89 with the help of the forward-flux sampling technique 90,91 . The latter seems like a promising approach for nucleation simulations 35,71,76,89,[92][93][94] although there are of course many other free energy and enhanced sampling techniques 70,[95][96][97][98][99][100][101][102] that could be used. Improvement in the water-surface interaction potential is of equal importance if one wishes to investigate heterogeneous ice nucleation.…”

“…Because of the length scale involved (nm), insights into the nucleation process can be obtained instead from computer simulations. And indeed, in the last few years a handful of computational studies have been successful in simulating heterogeneous ice nucleation [25][26][27][28][29][30][31][32][33][34][35][36][37] . This indicates that the time is now ripe for furthering our understanding of the microscopic factors that make a material a good INA.…”