[Pw_forum] Conversion of total energy to stress tensor

[Lorenzo Paulatto]

Dear Afshin,
it is not possible to convert total energy to stress; stress can be
computed from the same ingredients (wavefunctions, self-consistent
potential) as the total energy, but not just from the value of energy
itself.

pw.x can compute the stress of any give structure, you have to set
"tstress=.true." in the &control namelist, but of course you have to do it
before starting the calculation.

kind regards.

p.s. repeating your question every 8 hours won't increase the chance of
getting an answer, especially on Sunday

On 25 September 2016 at 17:49, Afshin Arjangmehr <ms.arjangmehr at gmail.com>
wrote:

> Dear QE developers and users,
>
> I have been able to calculate the total energy of crystalline structures
> under various strain tensors using pwscf. Now I intend to convert the total
> energy to stress tensors and then study the mechanical properties (either
> elastic or plastic) of different materials under strain (I have seen
> several papers that directly use E vs. Strain to calculate 2nd, 3rd, 4th,
> ... elastic constants and find yield & ultimate stress, but I believe that
> as Caro et al. http://dx.doi.org/10.1088/0953-8984/25/2/025803 mentioned,
> using Stress-Strain curve produces much accurate results).
> So, can anyone kindly give me some recommendation on how to convert Etot
> to Stress tensor? or Is there any tool to do this conversion? , since
> simply using (-dEtot/dVol) is not the solution
>
>
> Regards
>
> --
> With Best Regards
> Afshin Arjhangemehr
> PhD student in Radiation Application
> Shahid Beheshti University G.C, Tehran, IRAN
> (+98) 912 439 20 64
>
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> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>



-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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