Time acceleration in Elongation problem


I am using the LAMMPS version LAMMPS-64bit-19Sep2019. I tried to use Local hyperdynamics for an elongation problem in order to get the stress-strain response of the material at low strain-rates (close to fidelity). An error popped up saying that hyperdynamics cannot be used with ‘deform’ (used for elongation). So, could you please let me know if there is a way to get a low strain-rate (~1000-10000 s-1 ) for the elongation problem as above (in nano units)?

I look forward to hearing from you soon. Thank you very much in advance for your time and help.

With best wishes,
Arunjyoti Sinha Roy.

Hello Arunjyoti, one of the approaches for stress-strain computations is using indeed fix deform to achieve a continuous deformation. The other is a discretized version of the same, using a series of simulations at constant unit cell separated by change_box commands.

If you are using hyperdynamics to enhance the configurational sampling of the material, you will most likely need stationary conditions for it. Or if not, the domain partitioning of local hyperdynamics will probably need a constant unit cell.

I would suggest doing 2-3 steps of elongation with and without local hyperdynamics, so that you can compare them and see if LH has any effect.


Hello Giacomo,
Thank you very much for your reply. I will surely try out the multi-step deformation using hyperdynamics alternately (if that’s what you mean).