Hi everyone,
Attached is a script to calculate the thermal conductivity with Forcite using the imposed-flux method. In this method kinetic energy is exchanged between two fixed layers, repeatedly during a molecular dynamics simulation. Consequently energy flows between the layers. The system responds by creating a temperature gradient. The thermal conductivity follows as the ratio of flux and gradient.
The script implements both the fixed flux method of Jund [1] and the variable flux method of Müller-Plathe [2]. The script supports exchange of kinetic energy of atoms, molecules, repeat units, or sub units. Optionally you can calculate temperature and density fields to visualize the results:
To run the script you must provide a 3d atomistic structure. You can create input structures using Amorphous Cell module in Materials Studio. For best performance the system should be extended in the z-direction, corresponding to the direction of the flux. Further instructions, and a description of the input parameters and output study table data, is provided in a pdf document.
An example run is included for argon at 500 K and density 0.2652 g/cc. The script predicts a thermal conductivity of 0.0337 W/m/K, compared to 0.0355 W/m/K experimentally.
Please note the disclaimer: This custom script is compatible with Materials Studio version 5.5. It is provided "as is" and is NOT supported by Accelrys nor is it warranted for any purpose whatsoever. The user assumes responsibility for any malfunctions or bugs.
Hope it is of use to anyone!
Reinier
- Jund, P.; Jullien, R., "Molecular dynamics calculation of the thermal conductivity of vitreous silica.", Phys. Rev. B, 59, 13707-13711 (1999).
- Müller-Plathe, F., "A simple nonequilibrium molecular dynamics method for calculating the thermal conductivity.", J. Chem. Phys., 106, 6082-6085 (1997).
