Dear Lammps users,

I’m shearing my model with displacing the upper block with fix move command, fixed the bottom layer and let middel mobile under nvt.

And I using two method to calculate the stress (press)

(I)

compute stress all stress/atom NULL

compute Supper upper reduce ave c_stress[5]

compute vor all voronoi/atom

compute Sv all reduce ave c_vor[1]

variable stress_atom equal c_Supper/c_Sv/10 #bars to Mpa

(II)

compute Fx upper reduce sum fx

variable Fshear equal (c_Fx/lx*ly)*160217.66208 #ev/A to MPa

The result of (I) is 10 times to (II)

Can anyone tell me where is wrong?

Best wishes,

Jeaha