Accurate representation of hydrogen in molecular dynamics simulations is challenging. Due to the light mass of hydrogen, the molecule is strongly influenced by quantum effects, in particular at low temperatures. Classical force fields and simulations do not account for these quantum effects.
LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) is a widely used open-source molecular dynamics simulation code.
Despite its popularity and versatility, LAMMPS has not yet had any accurate force fields for hydrogen. To address this limitation, within the AUS framework of Sigma2, our team at NTNU-IT (Anders Christensen and Vishist Sharma) and Porelab – SFF (Øivind Wilhelmsen, Morten Hammer and Thuat T. Trinh) have developed a new code called Mie-FH in LAMMPS.
The new code is based on Mie potentials that have Feynman-Hibbs correction terms of first and second order to semi-classical account for the quantum effects of hydrogen. The new force fields are suitable for simulations with hydrogen, helium, neon, deuterium and mixtures with these components at temperatures above 20 K. In the research centre of Excellence (SFF) called Porelab, the new force field will be used to study porous materials for transport and storage of hydrogen.
The new code is written in C++ and is fully compatible with LAMMPS, enabling users to easily perform accurate quantum nuclear-corrected simulations. Extensive benchmark tests have been conducted on the Betzy supercomputer, demonstrating excellent scalability for medium and large systems. The successful integration of Mie-FH into LAMPPS and its strong performance on supercomputers highlight the potential of this code to significantly improve the reliability and efficiency of molecular dynamics simulations involving light elements such as hydrogen or helium.
Mie-FH is available now on GitHub. We invite users to try out the code, provide feedback, and contribute to its development.