Dear Lorenzo, Thank you very much. Surprisingly, I have considered tstress=.true. in my calculations without knowing what exactly it does and as I reviewed my output files, I found the stress matrix in Ry/bohr^3 (kbar). I appreciate for your kind and helpful response once again.
Regards Afshin On Sun, Sep 25, 2016 at 11:33 PM, Lorenzo Paulatto < [email protected]> wrote: > 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 <[email protected]> > 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 >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> 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 > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- 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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