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Re: [lammps-users] temp doesnt increase during equilibration
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Re: [lammps-users] temp doesnt increase during equilibration


From: Wes Barnett <w.barnett@...668...>
Date: Thu, 24 Aug 2017 13:10:48 -0400



> On Thu, Aug 24, 2017 at 5:53 AM, Meral Sharkas via lammps-users <lammps-users@lists.sourceforge.net> wrote:
>> I am trying to equilibrate my system at 300 k and 0 bar, my system is starting at high pressure so I relaxed my box at 0 k and used nve/lim to control the pressure. When I tried to raise the temperature to 300 k I found that the max temp reached was 30 k. May I ask what would be the reason for that?
>>
>> timestep 0.001
>>
>> fix  2 all npt temp 1 300.0 100 iso 0.0 0.0 1000

On Thu, Aug 24, 2017 at 11:36 AM, Stefan Paquay <stefanpaquay@...24...> wrote:
> I'm thinking that it is a problem with your temperature time constant. Nosé-Hoover thermostats can take a long time to equilibrate. Try reducing the time constant to something smaller.

I would add that the manual recommends setting Tdamp to around 100 *timesteps* and is written in *time units*. So instead of 100 for Tdamp, 0.1 would be more realistic given the time step of 0.001. Pdamp can be adjusted likewise.


--
James "Wes" Barnett
Postdoctoral Research Scientist
Department of Chemical Engineering
Kumar Research Group
Columbia University
w.barnett@...668...