Stress tensor units in VASP

[jmoon17]

Hi,

Using ISIF = 2, I see the stress tensor shown below in OUTCAR. The units are in kB.

I am trying to calculate the viscosity from the autocorrelation of the stress tensors but I am a bit confused about the units. How do I convert the units to force/area correctly? Do I just use the area as the 19 A by 19 A from simulation cell domain of (19 by 19 by 19 A) and divide them myself? I am new to VASP so any detailed replies will be very helpful!




FORCE on cell =-STRESS in cart. coord. units (eV):
Direction XX YY ZZ XY YZ ZX
--------------------------------------------------------------------------------------
Alpha Z 3337.27325 3337.27325 3337.27325
Ewald -13766.64398-13378.95460-12267.70626 394.53466 313.37856 -411.30460
Hartree 4460.49785 4584.62850 5376.77117 228.27932 169.74402 -297.23216
E(xc) -5556.75762 -5554.11176 -5550.36199 1.63334 1.65833 -1.51841
Local -5261.77220 -5716.82918 -7575.62141 -597.73557 -459.36174 680.91225
n-local 1528.58188 1536.92086 1539.29470 4.19145 2.83248 -4.47476
augment 575.38997 578.42817 580.80399 1.23329 1.29091 -1.45153
Kinetic 14672.07661 14616.03617 14552.63714 -29.37575 -38.67712 38.64452
Fock 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
-------------------------------------------------------------------------------------
Total -11.35425 3.39142 -6.90940 2.76076 -9.13455 3.57532
in kB -2.28664 0.68300 -1.39149 0.55599 -1.83962 0.72004
external pressure = -1.00 kB Pullay stress = 0.00 kB

[marie-therese.huebsch]

Hi jmoon17,

Sorry, your post has been unanswered for so long! Did you find the solution?
If yes, it would be very kind of you to share your insights here. If not, could you please provide a minimal example (INCAR, KPOINTS, POTCAR, POSCAR, OUTCAR) and the VASP version you are using. I would be happy to look into it.

Best regards,
Marie-Therese