[Pw_forum] small negative stress after optimization

[bahadir]

Hi

i get a small stress (0.31 KBar) after optimization of my system. I 
could not be able to exact 0.0KBar for the optimization calculations. I 
wonder if does it effect on other results such as band structure and 
especially phonon calculations.

Is it possible to get 0.00 KBar stress after optimization? My energy 
threshold is 10E-14 and force threshold is 10-8.

thank you

P.S:  i tried different ecut and k-grid sampling but, nothing helps, i 
always get a small negative or positive stress.