Speeding-up Hybrid Functional based Ab Initio Molecular Dynamics using Multiple Time-stepping and Resonance Free Thermostat

TL;DR

This paper introduces a method to significantly accelerate hybrid functional ab initio molecular dynamics, enabling practical simulations of complex systems and reactions that were previously computationally prohibitive.

Contribution

The authors develop a novel approach that speeds up hybrid functional AIMD by over 30 times, making high-accuracy simulations feasible for larger systems.

Findings

Achieved ~30x speed-up in hybrid functional AIMD simulations.

Enabled study of complex condensed matter systems with hybrid functionals.

Made hybrid functional AIMD comparable in speed to GGA-based methods.

Abstract

Ab initio molecular dynamics (AIMD) based on density functional theory (DFT) has become a workhorse for studying the structure, dynamics, and reactions in condensed matter systems. Currently, AIMD simulations are primarily carried out at the level of generalized gradient approximation (GGA), which is at the 2nd rung of DFT-functionals in terms of accuracy. Hybrid DFT functionals which form the 4th rung in the accuracy ladder, are not commonly used in AIMD simulations as the computational cost involved is $100$ times or higher. To facilitate AIMD simulations with hybrid functionals, we propose here an approach that could speed up the calculations by ~30 times or more for systems with a few hundred of atoms. We demonstrate that, by achieving this significant speed up and making the compute time of hybrid functional based AIMD simulations at par with that of GGA functionals, we are able to study several complex condensed matter systems and model chemical reactions in solution with hybrid functionals that were earlier unthinkable to be performed.