“…7 , 11 , and 12 , show that the nucleation process takes longer to reach states IV from state I when proceeding via the one-step pathway, implying that a larger energy barrier exists along this nucleation pathway. This qualitatively agrees with CNT and previous studies 29 , 92 , which showed that the free energy barrier for ice nucleation rises as T increases. Fig.…”
Section: Resultssupporting
confidence: 93%
“…The elevated free energy barrier will correspond to a larger critical nucleus. For example, in our system, the size of the critical nucleus for the classical pathway also increases with temperature (i.e., the total number of ice molecules = 475, 593, and 665 when T = 230, 240, and 250 K, respectively), which agrees with CNT and previous work 29 . As a result, the potential energy difference between the two TSs along the two pathways will increase with nucleus size.…”
Ice nucleation on the surface plays a vital role in diverse areas, ranging from physics and cryobiology to atmospheric science. Compared to ice nucleation in the bulk, the water-surface interactions present in heterogeneous ice nucleation complicate the nucleation process, making heterogeneous ice nucleation less comprehended, especially the relationship between the kinetics and the structures of the critical ice nucleus. Here we combine Markov State Models and transition path theory to elucidate the ensemble pathways of heterogeneous ice nucleation. Our Markov State Models reveal that the classical one-step and non-classical two-step nucleation pathways can surprisingly co-exist with comparable fluxes at T = 230 K. Interestingly, we find that the disordered mixing of rhombic and hexagonal ice leads to a favorable configurational entropy that stabilizes the critical nucleus, facilitating the non-classical pathway. In contrast, the favorable energetics promotes the formation of hexagonal ice, resulting in the classical pathway. Furthermore, we discover that, at elevated temperatures, the nucleation process prefers to proceed via the classical pathway, as opposed to the non-classical pathway, since the potential energy contributions override the configurational entropy compensation. This study provides insights into the mechanisms of heterogeneous ice nucleation and sheds light on the rational designs to control crystallization processes.
“…7 , 11 , and 12 , show that the nucleation process takes longer to reach states IV from state I when proceeding via the one-step pathway, implying that a larger energy barrier exists along this nucleation pathway. This qualitatively agrees with CNT and previous studies 29 , 92 , which showed that the free energy barrier for ice nucleation rises as T increases. Fig.…”
Section: Resultssupporting
confidence: 93%
“…The elevated free energy barrier will correspond to a larger critical nucleus. For example, in our system, the size of the critical nucleus for the classical pathway also increases with temperature (i.e., the total number of ice molecules = 475, 593, and 665 when T = 230, 240, and 250 K, respectively), which agrees with CNT and previous work 29 . As a result, the potential energy difference between the two TSs along the two pathways will increase with nucleus size.…”
Ice nucleation on the surface plays a vital role in diverse areas, ranging from physics and cryobiology to atmospheric science. Compared to ice nucleation in the bulk, the water-surface interactions present in heterogeneous ice nucleation complicate the nucleation process, making heterogeneous ice nucleation less comprehended, especially the relationship between the kinetics and the structures of the critical ice nucleus. Here we combine Markov State Models and transition path theory to elucidate the ensemble pathways of heterogeneous ice nucleation. Our Markov State Models reveal that the classical one-step and non-classical two-step nucleation pathways can surprisingly co-exist with comparable fluxes at T = 230 K. Interestingly, we find that the disordered mixing of rhombic and hexagonal ice leads to a favorable configurational entropy that stabilizes the critical nucleus, facilitating the non-classical pathway. In contrast, the favorable energetics promotes the formation of hexagonal ice, resulting in the classical pathway. Furthermore, we discover that, at elevated temperatures, the nucleation process prefers to proceed via the classical pathway, as opposed to the non-classical pathway, since the potential energy contributions override the configurational entropy compensation. This study provides insights into the mechanisms of heterogeneous ice nucleation and sheds light on the rational designs to control crystallization processes.
“…J is a key magnitude in characterising the nucleation phenomenon, since (1) it accounts for the likelihood of the system to undergo the liquid-crystal phase transition and (2) it can bridge predictions from experiments and computer simulations. Nonetheless, discrepancies in the nucleation rate of common substances, such as water, are currently under debate, not only between different simulation techniques 39,55,56 but also among different experimental setups. 5,6,57 Likewise, in hard-sphere colloidal crystal nucleation, a long-standing discrepancy among crystal nucleation rates from experiments and computer simulations still persists, 11,58,59 although several possible explanations have been recently discussed such as heterogeneous nucleation, 60 incomplete shear melting, 61 hydrodynamic effects on the crystal growth 62 and the nucleation rate 63,64 or sedimentation.…”
Section: Introductionmentioning
confidence: 99%
“…Some of these assumptions, such as the capillary approximation, 75 non-Markovian dynamics 76,77 or an inappropriate choice of the reaction coordinate 78,79 can lead to a breakdown of the CNT predictions. Nonetheless, CNT has also been shown to provide remarkably good predictions for many different systems such as for the liquid-crystal nucleation of the 3-D Ising model, 80 hard-spheres, 19,20 NaCl, 28 aluminum alloys, 81 supercooled high-pressure silica, 82 water, 20,56 and bubble nucleation of argon. 83 These several open debates clearly highlight the extreme complexity of the nucleation phenomenon.…”
Despite its lower stability and higher nucleation barrier, a metastable charge-disordered colloidal phase manages to parasitically crystallize from nuclei of the stable charge-ordered phase due to its enhanced kinetic crystal growth.
“…10 Among these methods, metadynamics 12 method shows great efficiency in accelerating crystallization and provides more control over exploration of the relevant phase space without pushing the system to excessively high free energy regions. 14 Many efforts based on metadynamics have been made on studying the nucleation mechanisms of ice, 15 silicon, 16 and other materials. 17,18 The metadynamics method requires appropriate collective variables (CVs), which enable the simulation to distinguish well between different local structures.…”
There exist various forms of crystalline silica in nature, 1 and silica is a commonly used fundamental constituent of glass. Many studies have been conducted on the properties of each type of crystal structure of silica and silica glass using experiments 2,3 and simulations. [4][5][6] Using varying heat treatment temperatures and suitable inducers or templates, silica of different degrees of crystallinity can be produced. [7][8][9] However, there is a lack of systematic research on partially ordered silica states, namely silica systems in between ordered and disordered states, due to their low probability of appearance in both experiments and simulations.Melting and nucleation are two primary approaches to the generation of silica structures between crystal and glassy phases. However, due to the high energy barrier
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