Mehrnaz Anvari wrote: > Hell > > I read your answers, but I think (it maybe wrong) after density > calculating in each step of vc-rx calculations, the program should use > it in the next step.
I don't know much about vc-rx calculation, but I can tell you for sure that in the relax calculations it does. The self-consistent charge density at the previous relaxation step(s) is(are) saved and used as initial guess for the next step. > so because of trivial changes in cell parameters trivial? > the number of iterations should decrease in each step, shouldn't? In principle it should, but if the atomic configuration changes a lot from a step to the other (as it can happen at the beginning of the relaxation) this cannot be guaranteed. > I have another question about introducing one layer to code. How could > I select c parameter along z direction ,I mean how large it should be? In principle with the option cell_dofree you could chose which of the lattice parameters you want to relax and which to keep fixed at the value specified on input. From previous posts I suspect this option is not always working as expected. You can try it and report problems, and possibly try/help to fix them if you are really interested in using it. > Could I say if stress along z direction become zero after 2-3 steps in > vc-rx my selection is correct? At the end of a variable cell calculation all stress components should be below the convergence threshold. If you want a lattice parameter to be fixed at a value other than the equilibrium one, either you try cell_dofree or implement constraints on cell parameters... Maybe I don't understand exactly what is your aim. GS > Best Regards > M.Anvari > Iran University Of Science & Technology > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- o ------------------------------------------------ o | Gabriele Sclauzero, PhD Student | | c/o: SISSA & CNR-INFM Democritos, | | via Beirut 2-4, 34014 Trieste (Italy) | | email: sclauzer at sissa.it | | phone: +39 040 3787 511 | | skype: gurlonotturno | o ------------------------------------------------ o
