arXiv subjects

Shifan Cui

Publications and source records attributed to Shifan Cui.

3 recordsLinked to original sources

arXiv2025

Finding the best density functionals for water: benchmarking the forces

A DFT benchmark on water including more than 50 functionals from GGA to double-hybrid levels is reported. The main metric is the accuracy of forces, allowing better structural coverage, higher statistical confidence, and fewer error sources compared to conventional benchmarks. The input structures include water clusters of 4~128 molecules, with highly varied yet realistic configurations of water, ice, and their mixtures. The B97M-V, {\omega}B97M-V, and revDOD-PBEP86-D4 functionals are found to be best on the mGGA, hybrid, and double-hybrid levels, respectively. No satisfying GGA functionals are found, but it can be obtained by combining BLYP-D4 with a simple correction to O-H bonds, achieving accuracy comparable to B97M-V.

physics.chem-ph↗

arXiv2022

Transition dynamics and metastable states during premelting and freezing of ice surfaces

The premelting of ice is well known, but little is known about how the premelted and solid surfaces convert to each other. In this work, the transition dynamics between two phases are revealed with large-scale molecular dynamics simulations. Supercooling and superheating states exist in the transition, and are overcome by nucleation-like processes. The natural inhomogeneity of ice surfaces enhances nuclei formation, while it only accelerates premelting but not freezing. Furthermore, the complete freezing of ice surfaces may be hindered by the stacking order mismatch between nuclei. This work points out the importance of metastable states in premelting, and the necessity of a large system scale in describing its transition process.

physics.chem-ph↗

arXiv2021

Premelting layer during ice growth: role of clusters

The premelting plays an important role in ice growth, but there is a significant gap in our knowledge between the atomistic premelting surface structure and the macroscopic growth mechanism. In this work, using large-scale molecular dynamics simulation, we reveal the existence of clusters on premelting surface, as an intermediate feature bridging the gap. We show the spontaneous formation and evolution of clusters, and they form a stable distribution determined by the growth rate. We demonstrate how this stable distribution is related to the growth mode of ice, connected by the growth of clusters. We come to a bilayer-by-bilayer growth mode under simulation-reachable high growth rates, but another mechanism, namely "cluster stacking", is speculated to exist at lower growth rates. Our work builds a connection between the microscopic structure of premelting layer and the macroscopic growth of ice, making a step forward to the full understanding of premelting and ice growth.

physics.chem-ph↗