Unwanted torsion during tensile test of CuZr alloy

Hi LAMMPS users,

I am currently running a tensile test for a CuZr alloy as a part of my Masters project. The test is running almost fine but there is some slight torsion in the sample during the simulation. I have mentioned it to my supervisor and he says it’s the first time he sees this. He mentioned that the boundary conditions may be the issue. I going to try changing the boundary conditions to see if it solves the issue but meanwhile I wanted to see if any of you have experienced this issue before. If so, have you been able to solve it? I have attached the tensile script in case it helps. Any help will be greatly appreciated.


tensile.in (3.65 KB)