stress/pressure difference

[Timothy Sirk]

Hello All,

I'm a new CP2K user getting started. During a run (described below) I notice
that the instantenous pressure and Tr(stress)/3 aren't the same. Is there a
reason these should be different, if both are computed on the timestep?

At 2000 step
TEMPERATURE[K]               =                    1239.390
1179.619
PRESSURE[bar]                =          0.134371272773E+06
0.140564407286E+06
1/3 Trace(stress tensor):   1.08660849E+01 GPa

Polymer melt in a cubic unit cell using BLYP/DCACP, NVT at high temperature
T=1200, 500 atoms
       BASIS_SET DZVP-GTH
      POTENTIAL GTH-BLYP-DCACP-q4
       BASIS_SET DZV-GTH
       POTENTIAL GTH-BLYP-DCACP-q1

Cheers,
Tim
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