The Quest for Accurate Liquid Water Properties from First Principles

Area of Science:

• Computational chemistry
• Physical chemistry
• Materials science

Background:

• Accurate ab initio molecular dynamics (AIMD) models are crucial for understanding bulk water and its role as a solvent.
• Current AIMD models often use generalized gradient approximation (GGA) density functional theory (DFT) and approximate nuclear quantum effects (NQEs) with classical simulations at elevated temperatures.

Purpose of the Study:

• To evaluate the accuracy of the meta-GGA B97M-rV functional for simulating liquid water.
• To compare its performance against a computationally expensive dispersion-corrected hybrid functional (revPBE0-D3).
• To investigate the necessity of incorporating quantum nuclei in AIMD simulations.

Main Methods:

• Accelerated path integral molecular dynamics (PIMD) simulations were employed.
• The meta-GGA B97M-rV functional was used for the potential energy surface.
• Simulations were performed to calculate radial distribution functions, self-diffusion coefficients, and infrared spectra.

Main Results:

• The meta-GGA B97M-rV functional, with quantum nuclei, reproduced bulk water properties with accuracy comparable to the revPBE0-D3 hybrid functional.
• Key properties like radial distribution functions, self-diffusion coefficients, and infrared spectra were accurately captured.
• High-temperature classical simulations were shown to be inadequate for properly treating NQEs.

Conclusions:

• The meta-GGA B97M-rV functional offers a computationally efficient yet accurate approach for AIMD simulations of water.
• Accurate treatment of nuclear quantum effects is essential for reliable simulations of condensed-phase systems.
• This study highlights the importance of evaluating DFT functionals with quantum nuclei for quantitative accuracy.