Beam bending BCs

Hi, I am using fix move to do bending of a cantilever beam. So I give a constant velocity to a block of atoms at the edge. The other end I use fix setforce 0 0 0 for another group of atoms. My question is should I use F F F or S S S boundary conditions. I am expecting dislocation nucleation at the surface! Thanks

Mohamed

Hi, I am using fix move to do bending of a cantilever beam. So I give a
constant velocity to a block of atoms at the edge. The other end I use fix
setforce 0 0 0 for another group of atoms. My question is should I use F F F
or S S S boundary conditions. I am expecting dislocation nucleation at the
surface! Thanks

this question is too general to be answered directly and without
knowing more details.
why not use m m m? and i don't see what nucleation has to do with the
choice of boundary conditions.

with the information provided in the manual you should be able to make
an informed decision. the mailing list is not an "input file approval
service".

axel.

I don’t think there are more details need to be given! It is just a cantilever bending (nanowire) and I assume non periodic boundary conditions in all directions. There also might be someone who has done this simulation before and can offer advice. The documentation is not giving me enough information about these different BCs. I didn’t ask for input file approval from ‘anyone’, and I think my question is clear enough now for anyone who wants to offer help. Thanks

Mohamed

I don't think there are more details need to be given! It is just a
cantilever bending (nanowire) and I assume non periodic boundary conditions
in all directions. There also might be someone who has done this simulation
before and can offer advice. The documentation is not giving me enough
information about these different BCs. I didn't ask for input file approval

this is a strong statement. why do you think that? there really isn't
much that needs to be said and the documentation describes exactly
what each option does (or doesn't). everything else is a matter of
having a sufficient background knowledge and it is not the job of a
manual to provide that.

from 'anyone', and I think my question is clear enough now for anyone who
wants to offer help. Thanks

you may think what you want. so do i.

axel.

The difference between f and s boundaries
is that you will lose atoms if they move beyond
the fixed setting. For s, the box will continually
shrink-wrap around the extent of the atoms
and you shouldn’t lose any if they don’t move
too quickly.

Steve

Thank you so much Steve, I really appreciate your clarification.

Best,
Mohamed