Setting of langevin

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1

Dear all,

I am simulating the bombardment of an high energy Ga ion (30 KeV) to the center of Si membrane. I am using the thersoff/zbl potential for it. Such high energy bombardment causes damage and high temperature in membrane. Therefore, I use langevin thermostat together with the fix nve for the temperature control. However, I am confused about how to use langevin. My questions are:

  1. The langevin is applied to all atoms for thermostat or I need to create a thermo skin around the outlet of simulation region and langevin is only applied to the skin, like the Ref… My picture is the membrane can be regarded as INF at xy dimension. The boundary of the membrane should be at room temp (300 K).

  2. For the parameters of langevin, the Tstop is at 300 K, but what should be the value of Tstart? It is konwn that on bombardment point the temperature is up several thousand K.

Best regards,

Ben

Ref
Thermal effects in 10 keV Si PKA cascades in 3C–SiC
Journal of Nuclear Materials, Volume 385, Issue 3, 15 April 2009, Pages 572–581

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Those are questions about your model, not about LAMMPS.
You have to decide what you are trying to model and what
the appropriate boundary conditions are.

Steve