Hydrogen bond dynamics in heavy water studied with quantum dynamical simulations

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Understanding the hydrogen-bond network in water is crucial for many chemical and biological processes.
• Heavy water (D2O) exhibits unique properties due to deuterium's mass, impacting its dynamics and structure.
• Previous studies on H2O provide a basis for comparison, but D2O's quantum effects require specific investigation.

Purpose of the Study:

• To investigate the temperature-dependent structure and dynamics of the hydrogen-bond network in heavy water (D2O).
• To establish a direct link between molecular dynamics and vibrational spectra (linear and nonlinear).
• To assess the contribution of quantum effects, such as tunneling and nuclear quantization, to D2O dynamics.

Main Methods:

• Utilizing quantum dynamical simulations with an ab initio-based potential for water interactions.
• Explicitly treating molecular motion with quantum mechanics.
• Calculating and analyzing linear and nonlinear vibrational spectra.

Main Results:

• The study provides new insights into the rearrangement of the hydrogen-bond network in heavy water.
• Tunneling does not significantly contribute to D2O dynamics above its melting point.
• Nuclear quantization effects are non-negligible across all studied temperatures and become more pronounced near the melting point.

Conclusions:

• Quantum effects, particularly nuclear quantization, play a significant role in heavy water's hydrogen-bond network dynamics, especially at lower temperatures.
• The findings align with experimental observations on the structural properties and proton momentum distribution in supercooled water.
• The simulation approach effectively connects molecular dynamics with spectroscopic properties, offering a powerful tool for studying water systems.