[CP2K:1868] Re: methane in a water box with FIST

Fawzi Mohamed fa... at gmx.ch
Thu Mar 12 17:13:02 UTC 2009

On 12-mar-09, at 18:03, Axel wrote:

> On Mar 12, 11:39 am, Teodoro Laino <teodor... at gmail.com> wrote:
>> This is not possible (NPT ensemble supports only as possible  
>> thermostats
>> NOSE and CVSR).
>> I agree with you that LANGEVIN is just another kind of thermostat and
>> should stay between the
>> other thermostats. But it was developed as a different ensemble..  
>> maybe
>> one day it will disappear
>> and reappear between the thermostats.. For the time being  I would
>> recommend you for this case
>> the CSVR . It's quite effective (have a look at the original paper).
> marius,
> two comments.
> if i understood the CSVR algorithm correctly, it is actually
> not very different from using langevin dynamics with a small friction
> coefficient (which is what people using NAMD typically do, for
> example).

the main difference is that it influences only the total kinetic  
energy, (it does a langevin dynamics only for that).
It has many nice properties, but does not act differently on different  
parts of the systems and conserves the rotational moment.
Langevin dynamics is applied on all the particles, and so it might be  
more efficient at equilibrating imbalanced energy distribution within  
the system (you don't have to count only on energy transport in the  
system to equilibrate them).
On the other hand it influences the system in a more global way and  
does not preserve the rotational moment.


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