[gmx-users] Constraint and Temperature Drop in NVE

[Johnny Lu]

reading this post in maillist again:
https://mailman-1.sys.kth.se/pipermail/gromacs.org_gmx-users/2012-May/071225.html

I think that is exactly the same problem.


On Wed, Sep 3, 2014 at 10:24 AM, Johnny Lu <johnny.lu128 at gmail.com> wrote:

> Hi.
>
> After equilibrating with NVT (for 10,000 steps of 2fs) and then NPT
> (10,000 steps of 2fs with V-rescale thermostat at 300K), when I run NVE
> (0.5fs timesteps) with a harmonic restraint with force constant 4184kJ/mol
> rad^2, the temperature then fluctuate around 292 K (
> http://oi60.tinypic.com/sni5at.jpg) in gromacs 4.6.6.
>
> When I instead run NVE with same setting except without the constraint
> after the two equilibration steps, the temperature stays around 300K.
>
> What is the cause of this drop of temperature to 292K?
>
> Thanks again.
>
>
>