[gmx-users] temperature control

[Erik Lindahl]

Hi,

Are you really using 1 femtosecond for the coupling time, or did you  
mean 1 picosecond?

The values in the mdp file are given in picoseconds; if you don't get  
the correct temperature
I would first try to use a shorter coupling time, say 0.1 picoseconds.

Cheers,

Erik

On Wednesday, Mar 19, 2003, at 22:46 US/Pacific, B. Nick wrote:

>
> Dear all,
>
> I want to run a MD simulation of a 74 atoms
> solute in 1600 SPC water molecules at 371 K.
> I coupled each group (solute and solvent)
> separately to the temperature control.
> If I analyze the temperature after MD
> I see that the solute is about 370 K whereas
> the water cools down to 251 K during the
> first ps of the run. This happens
> irrespectively of the thermostat and timestep.
> I used Berendsen and Nose-Hoover with a timestep
> of 1fs or 0.5 fs.
> Why isn't the temperature of both near 371 K?
> Can anyone explain this to me?
>
> Thanks in advance,
> Gitta
>
> --  
> Dr. Birgitta Nick
> Deutsches Wollforschungsinstitut
> Veltmanplatz 8, D-52062 Aachen, Germany
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------------------------------------------------------------------------ 
-----
Erik Lindahl, MSc, PhD     <lindahl at stanford.edu>
D109, Fairchild Building
Dept. Structural Biology, Stanford University School of Medicine
Tel. 650-7250754    Fax. 650-7238464