Research

Transformability: We have identified several transition pathways between ice crystals by MD simulations; Liquid-to-R-to-VII [PCCP, 2014]; XVII-to-Ic [Cryst. Growth Des. 2025]; Hydrogen-ordered Ic-to-IV [JPCL, 2024]; Hydrogen-ordered Ih-to-Md-to-XII [JPCC, 2024]; Md-to-Md2-to-VI [under review]. Ices R, Md, and Md2 are unreported ices we found.

Multi-twinned ices: Our MD simulations demonstrated that decahedral and icosahedral ice nanocrystals appear from liquid water droplets without violating the ice rule. The occurrence of multi-twinned nanocrystals aligns with the fact that natural polycrystalline snow crystals predominantly display 70.5-degree branches, which mechanism had been a mystery since the 1970s. We also showed the formation of multi-twinned ice nanocrystals within a fullerene. [ACS Nano 2024]

2D Nucleation on Ice: This study investigated the 2D nucleation and kinetic roughening on the ice basal face. We identified the presence of an ultra-low density water layer that assists 2D nucleation, and provided insights into the fundamental processes underlying the melt growth of ice crystal.[Comm. Mater., 2023]

Morphological Changes: This study examined the self-reorganization of the non-ionic surfactant C12E5 in water from hexagonal to lamellar phases. Findings indicated that the packing parameter alone is insufficient as an indicator, and the hydration shell must be considered. Dehydration during the phase transformation was linked to increased surfactant-related entropy, which drives the morphological change. [JCIS, 2023]

Close-packed.mp4

Close-packed Ices in Nanopores: Water molecules in any of the ice polymorphs organize themselves into a perfect four-coordinated hydrogen-bond network at the expense of dense packing. Even at high pressures, there seems to be no way to reconcile the ice rules with the close packing. Here, we report several close-packed ice phases in carbon nanotubes obtained from molecular dynamics simulations of two different water models. Typically, they are in plastic states at high temperatures and are transformed into hydrogen-ordered ice, keeping their close-packed structures at lower temperatures. Some of the simulated ices are found to exhibit ferroelectric ordering upon cooling. [ACS Nano, 2023]

Movie_iceVII.mp4

Rapid growth of ice VII and Plastic phase: Despite the abundance of water’s crystalline polymorphs, the growth mechanisms of most ice forms remain poorly understood. This study applies extensive MD simulations to examine the growth of ice VII, revealing a fast growth rate comparable to pure metals while maintaining robust hydrogen-bond networks. The results from an unsupervised machine learning applied to identify local structure suggest that the surface of ice VII consistently exhibits a bcc plastic ice layer, indicating the decoupling of translational and rotational orderings. The study also uncovers the ultrafast growth rate of pure plastic ice, indicating that orientational disorder in the crystal structure may be associated with faster kinetics. [Comm. Phys., 2023]

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Solid-liquid Critical Point: In nanoconfined environments, liquid water can transform into low-dimensional ices with unique properties. This study provided evidence for solid-liquid critical phenomena in carbon nanotubes. Both first-order and continuous phase changes between solid and liquid states were observed, with microscopic domains of both phases coexisting around the Widom line. This research deepens our understanding of phase transitions in nanoconfined water systems. [PNAS, 2015]

Antifreeze Glyco-proteins: Antifreeze glycoproteins (AFGPs) help organisms survive in subzero environments by inhibiting ice recrystallization. Molecular simulations reveal that hydrophilic and hydrophobic group segregation in the PPII helix is essential for ice binding. The selectivity for the primary prismatic plane results from its deeper cavities, and multiple, weak binding sites contribute to AFGPs' exceptional ice recrystallization inhibition activity. [JACS, 2018]

Ligand Binding: We introduce a conformational factorization approach that reduces local minima by reusing distant group configurations. This method analyzes binding site impact on free energy differences and employs efficient sampling techniques. Benchmarking on human aldose reductase shows convergence with 80% protein rigidity, 14 Å from the binding site. [PCCP, 2014]

Homogeneous Ice Melting: Upon heating, ice transforms into liquid water through the formation and growth of melting nuclei. In this study, molecular dynamics simulations reveal that the crucial first step in homogeneous ice melting is the spatial separation of defect pairs. Once separated, these pairs become entropically stabilized or "entangled," allowing defects with threefold hydrogen-bond coordination to persist and grow, setting the stage for rapid melting. [Nature, 2013]

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