Re: [ESPResSo-users] Thermostat

[Christoph Junghans]

Am 04/06/2011 02:21 PM, schrieb Muhammad Anwar:
> Hi,
> Dear Users,
> I am using Langevin thermostat, and i am trying to set the temperature
> of the MD simulation 300 K, I entered the thermostat as
>
> thermostat langevin 300 1.0
>
> then to check the temperature
> set Temp [expr [analyze energy
> kinetic]/$n_part/([degrees_of_freedom]/2.0)] // No rotation just
> translaional dof are included.
>
> puts -nonewline "run $i at time=$time, Temp= $Temp (2.3566e-09), tempe=
> [setmd temperature] (300.0)"
>
> They both have different values, should not they be same?
>
> Secondly i used temp in KT by putting
> set T 300
> set kT [expr $T * 1.38e-23/epsilon(kcal/mol)]
> thermostat langevin $kT 1.0
> i found following message
You have to put the temperature in reduced units, that usually means
T has units of kT/epsilon, see:
<http://matdl.org/matdlwiki/index.php/softmatter:Reduced_units>

Cheers,

Christoph
> Failed upon creating one of the monomers in Espresso!
> Aborting...
>
> Can anybody help in setting the temperature? Thank you very much.
>
> Best regards,
> Muhammad Anwar

--
Dr. Christoph Junghans
Max Planck Institute for Polymer Research
Theory Group
POBox 3148
D 55021 Mainz, Germany

Phone: +49 6131 379 335
Web: http://www.mpip-mainz.mpg.de/~junghans