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1

How can I design a spot heater in LAMMPS?

Let’s assume that I have a 100A100A20A block containing 22000 carbon atoms in my system. I want a heater of diameter 15A at the center of this rectangular block heated at a specific temperature (ex: 700K). I will introduce some other molecules close to the surface later to see their interaction with the heated and non heated surface region. Could anyone kindly suggest to me what should be the thermostat/ fix/ ensemble settings for the heater and the non-heater region in the simulation?

Any sort of help would be highly appreciated. Thank you.

Best regards,
Shahriar Mufid Rahman,
Research Assistant,
Dept of Mechanical Engineering,
Texas Tech University,
Lubbock, TX, 79415.

2

You could define a spherical region with the region command and then define a dynamic group via the group command using that region. Then use your thermostat of choice on that dynamic group. Then you could create another dynamic group (using subtract keyword) that contains all atoms not in that spherical group. Then use a different thermostat on that second dynamic group.

3

or you could use a thermostat bias (https://lammps.sandia.gov/doc/Howto_thermostat.html), that would also work for fixes like fix nvt where time integration and thermostat are combined. the dynamical group approach requires using a non-thermostat time integration fix and a non-time-integration thermostat.

axel.