commands help needed

May 13th

Hello,

I want to heat the atoms on the surface of Cu(copper) . Additonally, the surface of Cu is changed as the heating process proceeded. Like the picture shows.

The commands that I used are the fix temp/rescale command and compute temp/region command . What can I do if I want to get the surface region correctly

Nafens

mail1.pdf (175 KB)

May 13th

Hello,

I want to heat the atoms on the surface of Cu(copper) . Additonally, the
surface of Cu is changed as the heating process proceeded. Like the picture
shows.

The commands that I used are the fix temp/rescale command and compute
temp/region command . What can I do if I want to get the surface region
correctly

there is far too little information here
provide reasonable advice. for MD simulations
there are almost always multiple ways to do
(almost) the same thing and nothing is ever
entirely correct or entirely wrong (but chances
are that you are more wrong than right).

what exactly is your model and what process
are you trying to model?

how do you determine "correct" and what
kind of result or property, what level of accuracy
and overall what kind of answer do you
expect to extract from your simulations.

just throwing out a couple of keywords does
not suffice as a description. nobody here is
a mind reader...

axel.

I don't know if you have discovered the "fix heat" command, but you
can use it to add heat to some of the atoms in a lammps simulation in
a specific location (or a group):
http://lammps.sandia.gov/doc/fix_heat.html
You probably want to use the "region" keyword and supply a region-ID.
The documentation says you can create a a disc-shaped region on the
surface (where you want the heat to go) using the "region" command
(with the "cylinder" style).
http://lammps.sandia.gov/doc/region.html
(You still have to figure out how to model the copper surface, and
calculate how deep the laser radiation penetrates into that surface,
and choose the width of the copper slab. I assume you are simulating
heating by a laser.)
I hope this helps a little bit.

Andrew

P.S. By the way, in an earlier post you stated you wanted the size of
the hot spot on the surface to increase over time. I don't think "fix
heat" can do that. (But I don't understand why you want to do that.
I assume you are simulating laser heating. This is not my area of
expertise, but I'm not aware of a laser whose beam-width changes
during very short time intervals.) There are probably more serious
issues which I haven't even thought about.