Hexagonal ice density dependence on interatomic distance changes due to nuclear quantum effects
Lucas T S de Miranda1, Márcio S Gomes-Filho2, Mariana Rossi3
1Institute of Theoretical Physics, São Paulo State University (UNESP), Campus São Paulo, São Paulo, Brazil.
The Journal of Chemical Physics
|September 4, 2025
Summary
Machine learning potentials reveal most theoretical models overestimate hexagonal ice density. Quantum nuclear effects further increase this discrepancy, strengthening hydrogen bonds in ice Ih.
Area of Science:
- Condensed Matter Physics
- Computational Chemistry
- Materials Science
Background:
- Hexagonal ice (ice Ih) is the most common form of ice, exhibiting complex properties.
- Accurate theoretical models for ice Ih density and interatomic interactions are crucial for understanding its behavior.
- Machine learning potentials offer a promising approach to bridge ab initio accuracy with classical molecular dynamics scalability.
Purpose of the Study:
- To investigate the structural and vibrational properties of ice Ih using machine learning potentials.
- To evaluate the impact of different exchange-correlation functionals on ice Ih simulations.
- To understand the role of nuclear quantum effects on the density and hydrogen bonding in ice Ih.
Main Methods:
- Development and application of machine learning potentials derived from various exchange-correlation functionals.
- Simulations of hexagonal ice (Ih) focusing on structural and vibrational properties.
- Inclusion of nuclear quantum effects in the simulations.
Main Results:
- Most tested functionals overestimate the density of ice Ih compared to experimental data.
- Quantum treatment of nuclei exacerbates the density overestimation, deviating further from experimental values.
- Nuclear quantum effects were found to strengthen hydrogen bonds in ice Ih, unlike in water clusters or bulk water.
Conclusions:
- Current machine learning potentials, particularly with quantum nuclear treatments, require refinement for accurate ice Ih density prediction.
- Understanding the interplay of interatomic interactions and nuclear quantum effects is key to improving theoretical models of ice Ih.
- The distinct effect of nuclear quantum effects on hydrogen bonding in ice Ih warrants further investigation.
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