[Pw_forum] stress calculation for 2-D materials in quantum espresso

[Rajdeep Banerjee]

Dear all,
            I have a few confusions regarding calculation of stress-strain
relationship in quantum espresso for two-dimensional materials:

             1. does the stress tensor calculated in quantum espresso for a
two-dimensional material like graphene have unwanted contributions due to
presence of vacuum region? If yes, how does one calculate an 'equivalent
stress' removing those components?
             2. Does dividing the stress components by (Z/d) where  Z is
the supercell length in z-direction and d is the layer thickness/
inter-layer spacing will help in any way?
              3. because for 2-D materials stress is in N/m, can one just
multiply the components by the area of the unit cell corresponding to the
strain to get the units right?

               Any help is highly appreciated.

Thanks and regards,
Rajdeep Banerjee
PhD student
JNCASR,
Bangalore, India
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