Freezing in the vicinity of water-vapor interfaces is of considerableinterest to a wide range of disciplines, most notably the atmospheric sciences.In this work, we use molecular dynamics and two advanced sampling techniques,forward flux sampling and umbrella sampling, to study homogeneous nucleation ofice in free-standing thin films of supercooled water. We use a coarse-grainedmonoatomic model of water, known as mW, and we find that in this model avapor-liquid interface suppresses crystallization in its vicinity. Thissuppression occurs in the vicinity of flat interfaces where no net Laplacepressure in induced. Our free energy calculations reveal that the pre-criticalcrystalline nuclei that emerge near the interface are thermodynamically lessstable than those that emerge in the bulk. We investigate the origin of thisinstability by computing the average asphericity of nuclei that form indifferent regions of the film, and observe that average asphericity increasescloser to the interface, which is consistent with an increase in the freeenergy due to increased surface-to-volume ratios.
展开▼
