Re: question about NPT

From: Boyang Wang (pkuwangboyang_at_gmail.com)
Date: Thu Jan 19 2012 - 04:03:21 CST

Hi Oguz,

there are two parameters you can change,

langevinPistonPeriod 100.
langevinPistonDecay 50.

Please read the manual for more information.

Boyang

On Thu, Jan 19, 2012 at 5:51 PM, oguz gurbulak <gurbulakoguz_at_yahoo.com>wrote:

> Dear Boyang,
>
> Thanks for the reply. How can I increase the Langevin piston's mass in the
> configuration file ? I couldn't find any keyword in conf file to do it ?
>
> Thanks for your help.
>
>
>
>
> ------------------------------
> *From:* Boyang Wang <pkuwangboyang_at_gmail.com>
> *To:* oguz gurbulak <gurbulakoguz_at_yahoo.com>
> *Cc:* namd-l_at_ks.uiuc.edu
> *Sent:* Thursday, January 19, 2012 10:16 AM
> *Subject:* Re: namd-l: question about NPT
>
> Hi Oguz,
>
> pressure fluctuates a lot in NPT ensemble, because the volume fluctuates a
> lot. If you would like smaller fluctuation of pressure, you can increase
> the Langevin piston's mass in the configuration file.
>
> Boyang
>
>
> On Wed, Jan 18, 2012 at 4:06 PM, oguz gurbulak <gurbulakoguz_at_yahoo.com>wrote:
>
> Dear All,
>
> I performed md simulations in NPT ensamble and got -1000 atm pressure
> value for the system. My aim is to find 1 atm pressure value instead of a
> negative pressure value. Is this problem indicates that the force field
> I use is not appropriate for my system ? or Is this a problem caused by the
> langevin parameters ?
>
> why the system did not reach the target pressure value? Could you please
> share your thoughts about this problem ?
>
> Kind regards.
>
>
>
>
> --
> Boyang Wang, Ph.D.
>
>
>
>

-- 
Boyang Wang, Ph.D.

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