Cauchy stress tensor calculation

[musanna_galib]

Hello,

I found the hydro-static stress mentioned as external pressure in my OUTCAR.

I am a bit confused how vasp OUTCAR defines the deviatoric stress or cauchy stress tensor .
Can you please explain the cauchy stress tensor from the information of OUTCAR posted here?

Code: Select all

  FORCE on cell =-STRESS in cart. coord.  units (eV):
  Direction    XX          YY          ZZ          XY          YZ          ZX
  --------------------------------------------------------------------------------------
  Alpha Z  4240.32166  4240.32166  4240.32166
  Ewald   87475.62098 87723.30038************   165.98771   528.32304  -496.50672
  Hartree120898.70870121209.77210-98676.71517   -57.73425    26.07904  -373.79620
  E(xc)   -5174.66775 -5175.67391 -5172.79196     1.52099     2.39444    -1.05159
  Local  ************************226363.56706   -43.68310  -384.98566   848.76819
  n-local -2594.82310 -2588.94134 -2545.24439    -4.66335    20.36091    -5.78850
  augment  2383.51949  2386.70945  2358.07880    -3.56119   -11.50456     1.75552
  Kinetic  9126.56909  9180.15051  8966.63771   -60.00997  -181.07982    26.79565
  Fock        0.00000     0.00000     0.00000     0.00000     0.00000     0.00000
  -------------------------------------------------------------------------------------
  Total       2.64712     1.71045    -8.78076    -2.14316    -0.41262     0.17636
  in kB       2.31505     1.49589    -7.67926    -1.87431    -0.36086     0.15424
  external pressure =       -1.29 kB  Pullay stress =        0.00 kB

Thanks,
MG

[musanna_galib]

Can anyone help me?

[ferenc_karsai]

Please give us a few days to answer.

[ferenc_karsai]

The components of the total relevant stress tensor are given in the line "in kB". This is what I usually use. The other lines show the computational parts of the stress tensor. I've attached the relevant pages of Georg Kresse's thesis. The document is in German, but it contains the equations so that you can see how each term is calculated.