[Pw_forum] The recalculated pressure is beyond the range specified by press and press_conv_thr

[Tsung-Lung Li]

Dear QE Friends:

Below is an excerpt of my recent PW simulation,

----------------------------------------
&control
   :
   :
   calculation = 'vc-relax'
   restart_mode = 'from_scratch'
   etot_conv_thr = 1.0D-4
   forc_conv_thr = 1.0D-3
/
&ions
   ion_dynamics = 'bfgs'
/
&cell
   press = 0.001D0  ! kbar
   press_conv_thr = 0.2D0  ! kbar
/
----------------------------------------

The simulation converges.

A final scf calculation at the relaxed structure.
The G-vectors are recalculated for the final unit cell.

The last few lines containing "P=" are

grep "P=" t.log

total   stress  (Ry/bohr**3)                   (kbar)     P= 0.13
total   stress  (Ry/bohr**3)                   (kbar)     P= 0.19
total   stress  (Ry/bohr**3)                   (kbar)     P= 0.08
total   stress  (Ry/bohr**3)                   (kbar)     P= 3.17

The recalculation suggests a final pressure of 3.17 kbar, which is
BEYOND the specified range of
[0.001D0-0.2D0, 0.001D0+0.2D0] = [-0.19900, 0.20100].

Does this mean that the simulation does NOT converge to condition specified
in &cell section?  Or, do I make any mistake?

Thank you in advance.


Best Regards,
Tsung-Lung Li