Converged Colored Noise Path Integral Molecular Dynamics Study of the Zundel Cation down to Ultra-low Temperatures at Coupled Cluster Accuracy

Abstract

For a long time, performing converged path integral simulations at ultra-low, but finite temperatures of a few Kelvin has been a nearly impossible task. However, recent developments in advanced colored noise thermostatting schemes for path integral simulations, namely the Path Integral Generalized Langevin Equation Thermostat (PIGLET) and the Path Integral Quantum Thermal Bath (PIQTB), have been able to greatly reduce the computational cost of these simulations, thus making the ultra-low temperature regime accessible in practice. In this work, we investigate the influence of these two thermostatting schemes on the description of hydrogen-bonded systems at temperatures down to a few Kelvin as encountered, for example, in helium nanodroplet isolation or tagging photodissociation spectroscopy experiments. For this purpose, we analyze the prototypical hydrogen bond in the Zundel cation (H${}_5$O${}_2^{+}$) as a function of both, oxygen-oxygen distance and temperature in order to elucidate how the anisotropic quantum delocalization and, thus, the shape of the shared proton adapts depending on the donor-acceptor distance. The underlying electronic structure of the Zundel cation is described in terms of Behler's Neural Network Potentials of essentially converged Coupled Cluster accuracy, CCSD(T*)-F12a/AVTZ. In addition, the performances of the PIQTB and PIGLET methods for energetic, structural, and quantum delocalization properties are assessed and directly compared. Overall, our results emphasize the validity and practical usefulness of these two modern thermostatting approaches for path integral simulations of hydrogen-bonded systems even at ultra-low temperatures.

References in corpus (11)

• An Efficient and Accurate Car-Parrinello-like Approach to Born-Oppenheimer Molecular Dynamics
• Efficient stochastic thermostatting of path integral molecular dynamics
• Nuclear quantum effects in solids using a colored-noise thermostat
• Colored-noise thermostats à la carte
• Efficient first-principles calculation of the quantum kinetic energy and momentum distribution of nuclei
• Accelerating the convergence of path integral dynamics with a generalized Langevin equation
• Portable implementation of a quantum thermal bath for molecular dynamics simulations
• Zero-Point Energy Leakage in Quantum Thermal Bath Molecular Dynamics Simulations
• Nuclear quantum effects in ab initio dynamics: theory and experiments for lithium imide
• Quantum effects in graphene monolayers: Path-integral simulations
• High-dimensional neural network potentials for solvation: The case of protonated water clusters in helium