Extending Hamiltonian-Adaptive Resolution Simulation to Interfaces: An Updated LAMMPS Implementation and Application...

Many natural phenomena involve processes that happen simultaneously at different characteristic length- and timescales. Typically, the region where the process of interest happens is affected by fluctuations in its surroundings. Modeling these systems requires an effective combination of different simulation resolutions. The Hamiltonian-adaptive resolution simulation (H-AdResS) method allows us to model dual-resolution systems in length- and timescales compatible with molecular diffusion, by combining atomistic and particle-based coarse-grained models in the same simulation box. In this work, a new implementation of H-AdResS is provided in LAMMPS 2023. The new features extend the usage to more diverse interaction potentials and simplify the preparation of input files via dedicated LAMMPS input commands, while keeping the efficiency gain of the basis method. The implementation is benchmarked by reproducing water properties from a reference atomistic simulation. Importantly, the new implementation includes changes in compensation routines allowing simulation of systems with fluctuating density. As an example, the method in its new implementation is applied to model a porous metal-organic framework and its gas adsorption structure and transport properties. We demonstrate that structural and dynamic properties in the atomistic region of the dual-resolution scheme are unaffected and remain those of the fully atomistic system, while increasing simulation efficiency.