Re: [ESPResSo-users] Langevin vs. Berendsen thermostat

[Koen Nickmans]

Hi guys,

thanks for clearing that up so quickly! I was not aware of the global/local difference. I've listed the reference from the UG below, it would appear then that this reference is incorrect (if I understand correctly now in any case :) ) 

Thanks again,

Koen

Berendsen, H. J. C., Postma, J. P. M., Van Gunsteren, W. F., DiNola, a., & Haak, J. R. (1984). Molecular dynamics with coupling to an external bath. The Journal of Chemical Physics, 81(8), 3684. doi:10.1063/1.448118

On Fri, Apr 26, 2013 at 11:19 AM, Ulf Schiller <address@hidden> wrote:

On 04/26/2013 11:09 AM, Koen Nickmans wrote:

Dear all,

I'm sorry this is not so much Espresso related, but would somebody be so
kind as to point a master student in the right direction as to what the
difference is between the Langevin and Berendsen thermostats, if there
is one? The Espresso user guide lists a Berendsen paper as a reference
to the Langevin thermostat, hence my confusion.

Dear Koen,

The Berendsen thermostat is a global thermostat that rescales the velocities to match the temperature of the heat bath. While it thermalizes the system efficiently, it does not strictly generate a canonical ensembles. Therefore, it is often used to equilibrate a system.

The Langevin thermostat is a local thermostat that couples each particle independently to the bath. It consists of a frictional contribution and a random contribution and by means of the fluctuation-dissipation relation a correct canonical ensemble is generated. However, it does not include hydrodynamic correlations between particles.

Hope this helps,
Ulf

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