Fast Quasi-Centroid Molecular Dynamics for Water and Ice

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Centroid Molecular Dynamics (CMD) methods are crucial for studying nuclear quantum effects.
• Accurately modeling these effects in condensed-phase systems like water and ice remains challenging.
• Previous methods require significant computational resources or approximations.

Purpose of the Study:

• To adapt the fast quasi-centroid molecular dynamics (f-QCMD) method for condensed-phase systems.
• To investigate the impact of nuclear quantum effects on vibrational spectra of water and ice.
• To establish a consensus among modern CMD methods regarding these effects.

Main Methods:

• Approximating the quasi-centroid potential of mean force as inter- and intramolecular corrections.
• Utilizing a regularized iterative Boltzmann inversion to derive quasi-centroid distribution functions.
• Employing path integral molecular dynamics simulations.

Main Results:

• The f-QCMD method demonstrated good agreement with established QCMD dipole absorption spectra for liquid water.
• Satisfactory agreement was achieved for the vibrational spectra of ice.
• The results align well with spectra from a recent centroid molecular dynamics (CMD) implementation.

Conclusions:

• The f-QCMD method provides a computationally efficient and accurate approach for condensed-phase systems.
• Modern CMD techniques are converging on a consistent understanding of nuclear quantum effects in water and ice spectra.
• This work validates f-QCMD as a reliable tool for spectroscopic studies of condensed matter.