Configurational Entropy in Ice Nanosystems: Tools for Structure Generation and Screening

Area of Science:

• Physical Chemistry
• Materials Science
• Nanotechnology

Background:

• Low-temperature ice and water in nanoscale systems are subjects of recent experimental and theoretical interest.
• Theoretical modeling faces the proton-disorder problem, requiring exploration of numerous configurations for accurate low-energy isomers and entropy effects.

Purpose of the Study:

• To present an efficient, general-purpose program for searching and enumerating proton-configurational ensembles in hydrogen-bonded molecular systems.
• To apply this program to experimentally relevant ice nanosystems, specifically a boron nitride film-supported ice nanodot.

Main Methods:

• Development of a versatile computational program for finite, semiperiodic, and periodic hydrogen-bonded systems.
• Systematic generation and analysis of the proton-configurational ensemble for an ice nanodot.
• Benchmarking the program using ice nanotubes and finite slabs.

Main Results:

• Identification of a novel ice nanodot isomer with an energy approximately 1 eV lower than previously studied configurations.
• The identified isomer exhibits a significant dipole moment, indicating inherent ferroelectricity in ice nanodots parallel to the surface.
• Demonstration of hydrogen-bond connectivity parameters as effective tools for screening low-energy isomers.

Conclusions:

• The developed program efficiently addresses the proton-disorder problem in nanoscale ice.
• Ice nanodots supported on boron nitride films possess inherent surface-parallel ferroelectricity.
• Hydrogen-bond connectivity analysis provides a valuable method for identifying stable low-energy configurations in hydrogen-bonded nanomaterials.