pyHMA

pyHMA is a VASP post-processor (written in Python 3) for precise measurment of crystalline anharmonic properties using Harmonically Mapped Averaging (HMA) method. It is based on post-processing vasprun.xml output file(s) obtained from NVT Born-Oppenheimer ab initio molecular dynamics (AIMD) simulation. See Table 1 as an example for HMA expressions for anharmonic energy and pressure, along with direct/conventional (Conv) counterpart.

pyHMA is free software: you can modify and/or redistribute it under the terms of the Mozilla Public License (MPL 2.0).

Please cite this paper when using pyHMA package in your research:

Sabry G. Moustafa, Apoorva Purohit, Andrew J. Schultz, and David A. Kofke, pyHMA: A VASP Post-processor for Precise Measurement of Crystalline Anharmonic Properties using Harmonically Mapped Averaging, Comput. Phys. Commun., 2020.

Note

• The term anharmonicity is commonly used in literature to qualitatively describe a system with no equilibrium configuration at \(0\) K (i.e., imaginary frequencies); in other words, it refers to a “non-harmonic” potential energy surface.
• Here, however, we define anharmonic contribution of some property \(X\) as the residual in excess of the harmonic approximation; i.e., \(X_{\rm ah} \equiv X - (X_{\rm lat} + X_{\rm qh})\). Therefore, this specific definition is meaningless if the system does not have equilibrium lattice configuration at \(T=0\) K. For this reason, pyHMA checks forces on the first configuration to make sure the system has an equilibrium configuration (i.e., zero forces).

• Installation
• Usage
• Modules