heat flux when using langevin dynamics

From: Philipp Schön (phschoen_at_web.de)
Date: Thu Nov 01 2007 - 09:12:56 CDT

Dear Users,
I apply a constant heat flux across my simulation cell by heating/cooling two different regions in my box. And want to know now what is the heat flux I add/remove from these specific locations. How can I calculate that? For the velocity scaling I use a langevin damping constant of 1 ps and a time step of 1 fs. How can I get the heat in J/s?
If I use 0.61 W/mK for water as conductivity an someting like 10^9 K/m as thermal gradient (i.e. dT/dz) I got something like 10^9 W/m2K. If I calculate q via kinetic energy devided by 1ps I got two orders of magnitude difference or a "time constant of 100 ps". The velocity scaling cannot results something like this.
I cannot get information from the source code in which exact frequency heat is added when using langevin dynamics. Help is very much appreciated.
Thanks for your help
Cheers
Philipp
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