**An enhanced version of the heat exchange algorithm with excellent energy
conservation properties**

P Wirnsberger and D Frenkel and C Dellago, JOURNAL OF CHEMICAL PHYSICS, 143, 124104 (2015).

DOI: 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 et al. **Mol. Phys. 80,
1389 (1993); 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. (C) 2015 AIP Publishing LLC.

Return to Publications page