An enhanced version of the heat exchange algorithm with excellent energy conservation properties
Journal of Chemical Physics
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Wirnsberger, P., Frenkel, D., & Dellago, C. (2015). An enhanced version of the heat exchange algorithm with excellent energy conservation properties. Journal of Chemical Physics https://doi.org/10.1063/1.4931597
We propose a new algorithm for non-equilibrium molecular dynamics simulations of thermal gradients. The algorithm is an extension of the heat exchange algorithm developed by Hafskjold and co-workers [Mol. Phys. 80, 1389 (1993); Mol. Phys. 81, 251 (1994)], in which a certain amount of heat is added to one region and removed from another by rescaling velocities appropriately. Since the amount of added and removed heat is the same and the dynamics between velocity rescaling steps is Hamiltonian, the heat exchange algorithm is expected to conserve the energy. However, it has been reported previously that the original version of the heat exchange algorithm exhibits a pronounced drift in the total energy, the exact cause of which remained hitherto unclear. Here, we show that the energy drift is due to the truncation error arising from the operator splitting and suggest an additional coordinate integration step as a remedy. The new algorithm retains all the advantages of the original one whilst exhibiting excellent energy conservation as illustrated for a Lennard-Jones liquid and SPC/E water.
non-equilibrium molecular dynamics, NEMD, heat exchange algorithm, HEX, thermal gradient
PW gratefully acknowledges stimulating discussions with Chongli Qin, Clemens Moritz, Raman Ganti and Aleks Reinhardt, as well as financial support through a DOC Fellowship of the Austrian Academy of Sciences. Further financial support from the Federation of Austrian Industry (IV) Carinthia and the Austrian Science Fund FWF within the SFB Vicom (project F41) is acknowledged with gratitude. The results presented here have been achieved in part using the Vienna Scientific Cluster (VSC). DF acknowledges support from Engineering and Physical Sciences Research Council Programme Grant EP/I001352/1.
External DOI: https://doi.org/10.1063/1.4931597
This record's URL: https://www.repository.cam.ac.uk/handle/1810/250468
Attribution-NonCommercial 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by-nc/2.0/uk/
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