Boundary condition and minimization

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1

Dear all,

I want to simulate the uniaxial tension test in a nonowire by using molecular statics. The nanowire are subject to tension in x direction.
If boundary condition is p s s, then I can use the command displace_box to simulate the problem. However, I can not use that command if
boundary condition is s s s. I want to fix the nanowire at one end layer, then, moving atoms at the other layer along x direction. After each
increment the potential energy of the system is minimized to obtain the equilibrium state. Could you give any comments?

Thank you very much.
DucTam

2

In current LAMMPS, displace_box has been
replaced by change_box. If you remap the
atoms (an option in that command), you can
expand the box and atoms for periodic
or non-periodic systems. When you do
the minimization, you will likely need
to nail down the end atoms, or the
wire will just relax to its normal length.
You can do this with fix setforce 0.0
and enable it for minmization.

Steve

3

Dear Steve

Thank you very much for your useful comment.

Best wishes
Duc Tam