(683h) Implementation of Harmonically Mapped Averaging Methods in Popular Molecular Simulation Codebases

"Mapped averaging" is a recently published scheme for the reformulation of ensemble averages. The framework uses approximate results from statistical mechanical theory to derive new ensemble averages (mapped averages) that represent exactly the error in the theory. Well-conceived mapped averages can be computed by molecular simulation with remarkable precision and efficiency, and in favorable cases the speedup factors are several orders of magnitude. For crystalline systems, mapped averaging enables simulation to compute directly the anharmonic contribution to the properties, without noise contributed by harmonic behavior. The result is a technique for computing crystalline properties with unprecedented, transformative efficiency. The aim of this project is to implement these methods on well-established and widely used software packages for simulation of crystalline systems, and furthermore to develop mapped averages for new applications of interest to the users of these systems. Specifically, we are developing implementations for LAMMPS, HOOMD, Cassandra, and VASP, which altogether have a base encompassing thousands of users. Software elements implemented in this project are in many cases completely transparent to the users of these packages, and can be employed by them with no added complication, to speed up their calculations by orders of magnitude.

We describe our progress in this development and demonstrate mapped averaging methods on some of the targeted platforms.