[ESPResSo-devel] Implementing Lowe-Andersen thermostat

[Kai Szuttor]

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Hi everyone,

currently i´m trying to implement the Lowe-Andersen thermostat (C. P.
Lowe 1999 Europhys. Lett. 47 145 doi:10.1209/epl/i1999-00365-x) in the
Espresso source code and having some issues i wasn´t able to resolve.
So far i wrote a function that performs the thermalization of the
particles relative velocities. This function is called by the function
"integrate_vv" in integrate.cpp just after the GHMC thermostat is
doing its ghmc_momentum_update()-call. I thought that would a good
idea since the Lowe-Andersen thermostat is also only changing
particles velocities and not the forces acting on them.
The problem i'm having now is that the energy grows to infinity and i
was not able to find out why.
To check for the algorithm itself i implemented the thermostat on the
tcl-level and it seems to work, so the algorithm itself should do the
right thing.
Is there anything i should know about espressos internal structure
regarding the velocity handling? Maybe someone can give me a hint.

Thanks in advance.

Kai Szuttor
Insitute for Computational Physics
University of Stuttgart
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