[Pw_forum] Kind of Stress tensor

[Hörmann Nicolas Georg]

Dear Mahdi,


tstress=.true. prints the Cauchy stress. It is the internal instantaneous stress from the Calculation. The other stresses are two-point stresses e.g. relative to some initial and final configurations (for deformations).


The  quantum mechanical stresses are the internal stresses at the very cell parameters and Volume of the SCF calculation. They correspond basically to the expansion parameters of the total energy with respect to infinitesimal deformations.



 BR  Nico








Nicolas Hoermann

Theory and Simulation of Materials (THEOS)

EPFL, Lausanne






Dear all,

I know If I set tstress=.true. the stress tensor will be computed and
printed. but What's the kind of the Stress Tensor QE dose print? for
example Cauchy,
   true, Kirchhoff, PK2, ...
I am trying to calculate second Piola-Kirchhoff (PK2) stresses with QE.
Any suggestions or comments are appreciated.

Sincerely
Mahdi

*Mahdi FaghihNasiri*
Department of Physics
Shahrood University of Technology
Shahrood,Iran**
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