[lammps-users] wrong GNR strain-stress computation with AIREBO

Dear all,

I performed tensile deformations on the graphene sheet along zigzag direction using the fix deform command in a npt ensamble. The potential I used is AIREBO. Normally the stress should increase with the larger strain before the fracture point. In my case the stress-strain curve goes well before the fracture point suggest by previous papers (about 0.2 for zigzag deformation in a 10nm*10 nm graphene) but later the stress and the potential of the system go up steeply, and the sheet breaks at a strain about 0.4.

Why does the stress goes up when the strain is large? Could anyone give a suggestion? I have attached my input script and the result. Thank you in advance.

Best regards

Sincerely yours

tensile.eps (69.4 KB)

Maybe you are pulling too fast. Failure is
a function of strain rate and other equilibration


2011/1/10 <[email protected]>: