Nuclear Quantum Effects in Water at the Triple Point: Using Theory as a Link Between Experiments

Area of Science:

• Quantum mechanics
• Nuclear physics
• Computational chemistry

Background:

• The quantum nature of atomic nuclei leads to kinetic energy distributions deviating from classical models.
• Deep inelastic neutron scattering (DINS) experiments can measure these quantum effects.
• Directly probing nuclear quantum kinetic energy requires robust theoretical validation due to indirect environmental relationships.

Purpose of the Study:

• To compute the kinetic energy of hydrogen and oxygen nuclei in various water phases using advanced computational methods.
• To validate theoretical calculations against experimental equilibrium isotope fractionation data.
• To establish a reliable benchmark for linking fractionation experiments and DINS measurements for improved accuracy.

Main Methods:

• Path integral molecular dynamics (PIMD) simulations were employed to calculate nuclear kinetic energy.
• Simulations covered liquid, solid, and gas phases of water near the triple point.
• Three distinct interatomic potentials were compared, and results were validated against isotope fractionation measurements.

Main Results:

• Accurate computation of nuclear kinetic energy for hydrogen and oxygen in water across different phases.
• Validation of simulation results against experimental equilibrium isotope fractionation data.
• Demonstrated ability to link precise experimental measurements with theoretical simulations.

Conclusions:

• Advanced simulations provide a crucial link between experimental isotope fractionation and DINS measurements.
• This work establishes a benchmark for future nuclear kinetic energy studies.
• The findings offer insights to enhance the accuracy of interatomic potentials for water models.