[lammps-users] Thermal conductivity of silicon

Sreekant,

I do not think you need to rescale temperatures after NVT. Do you reach a stable temperature after all NVT steps? If not, check your drag coefficient or perform longer simulations. I would suggest to test your NVT and NVE simulations without the restart file option and verify around what temperature your system fluctuates during NVE. But, I am sure it is not an issue of the restart option.

A simple way to test that everything is working OK before long simulations, is to perform NVE steps only at a given initial temperature (without any rescaling steps, only initial velocities). Your system (Silicon) should equilibrate around 0.5*Tinit.

Javier Goicochea


Javier,
Yes, after NVT, it does appear that the temperature stabilizes at 300 K (with small oscillations around 300 K).

For NVE steps performed with a given Tinit, why would the system stabilize to 0.5Tinit?

Thanks,
Sreekant

— On Wed, 2/18/09, Javier Goicochea <[email protected]…24…> wrote:



> From: Javier Goicochea <[email protected]…24…>
> Subject: Re: [lammps-users] Thermal conductivity of silicon
> To: [email protected]
> Date: Wednesday, February 18, 2009, 1:10 AM
>
> Sreekant,
>
> I do not think you need to rescale temperatures after NVT. Do you reach a stable temperature after all NVT steps? If not, check your drag coefficient or perform longer simulations. I would suggest to test your NVT and NVE simulations without the restart file option and verify around what temperature your system fluctuates during NVE. But, I am sure it is not an issue of the restart option.
>
> A simple way to test that everything is working OK before long simulations, is to perform NVE steps only at a given initial temperature (without any rescaling steps, only initial velocities). Your system (Silicon) should equilibrate around 0.5
Tinit.
>
> Javier Goicochea
>
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Equipartitioning of energy between kinetic and potential.

Steve