how to add a gaussian heat resource

11th.October
Hello,
I want to add a gaussian heat source by fix temp/rescale command.
T® = Tmaxexp(-krr)
It is an atom-style variable ,but the Tstart of fix temp/rescale only support equal-style. So how could I add a gaussian heat source by fix temp/rescale?
I really appreciate for your help~
Nafens

                                                    11th.October
Hello,
I want to add a gaussian heat source by fix temp/rescale command.
T(r) = Tmax*exp(-kr*r)
It is an atom-style variable ,but the Tstart of fix temp/rescale only
support equal-style. So how could I add a gaussian heat source by fix
temp/rescale?

temp/rescale doesn't make any sense, since you have no real target temperature.

what you *can* do is use the velocity command to modify the current
velocities with an atom style variable. however, there are two
important issues to consider:
a) there is no "per atom" or "per location" temperature. temperature
is only defined for (large to infinite) ensembles and how much kinetic
energy is exchanged between them
b) every temperature rescaling is equivalent to kicking your system,
and thus create soundwaves that distort your results.

in general, i wonder what the utility of such a thermalization would
be. i could imagine this in macroscopic simulations, but on the
atomistic level, such operations are difficult to justify, since the
local temperature distributions are determined by material properties.

axel.

You could also look at modifying (or adding an option)

to the fix heat command, which adds KE to a system
in a regulated manner.

Steve

The intent of your Gaussian heat source is probably to generate local
heating in a small region. There are lots of ways you could do this.
Without modifying the code, you can use fix temp/rescale or fix
langevin with the following compute:

http://lammps.sandia.gov/doc/compute_temp_region.html