[Pw_forum] epsilon.x
Dear Dev, I also have never used this feature of the code but Doc directory has useful documents when you need answers: Doc/eps_man.tex It is clearly stated there that "the non-local contribution due to the pseudopotential is neglected. Actually the correction to the matrix element that take into account the non-local part of the Hamiltonian is not implemented." So to develop the code for USPP you need to find a way to calculate & add these corrections, I guess. You can check epsilon.f90 to learn more.. emine kucukbenli, Sissa, Italy SISSA Webmail https://webmail.sissa.it/ Powered by Horde http://www.horde.org/
[Pw_forum] tefield and LSDA II
Dear PWSCF developers, I just want to follow my previous email. After reading the code more carefully, I found in the subroutine input.f90 that if tefield = .true. and nspin > 2, then we have the error message that "LSDA not available with electric field". However, nspin > 2 or more precisely speaking nspin = 4 means non-collinear spin-polarized calculation. nspin = 2 is the standard spin-polarized calculation with magnetization along z direction. My question is when tefield = .true., can I do spin-polarized calculation with magnetization along z direction? The error message "LSDA not available with electric field" seems a little bit confusing to me. Thank you very much. Hanghui -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090927/4dd889af/attachment.htm
[Pw_forum] tefield and LSDA
Dear PWSCF developers, I found that when I turn on an external electric field (tefield = .true.), I can not do spin-polarized calculation (LSDA = .false.). I am just curious whether there is any fundamental difficulties to do spin-polarized calculation in the presence of an external electric field or it is just that this function is not implemented in QE. Thank you very much. Hanghui Chen Department of Physics Yale University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090927/a09bbf63/attachment.htm
[Pw_forum] equilibrium lattice constant determination
Dear QE users, i performed 'vc-relax' on GaAs to find out zero temperature lattice constant. i performed similar calculation of energy vs lattice const(a). If we consider energy to be stored in the field (which is present in the volume of the cell) then minimum of Energy/Vol vs 'a' should give the result. But instead the minimum of E vs 'a' is giving a result(the earlier graph isnt giving a minimum at all) in accordance with that given by vc-relax. I would be grateful to be clarified of the understanding of the physics of this situation. sincerely, -- Sreekar Guddeti IIT Bombay BTech + MTech Physics Dept IIT Bombay -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090927/445802d3/attachment.htm
[Pw_forum] epsilon.x
Sir, Problem is that it gives the error with mssg that USPPs are not implement. What to do in that case. Earlier to one of the answer Lorenzo Paulatto sir write The error means that the calculation you are trying to do is not implemented for USPP (ultra-soft pseudo-potential). Either use norm-conserving only, or develop it for ultrasoft. I didnt get how to develop it for ultrasoft PPs. Thanks Dev Sharma, Univeristy of Delhi On Sun, Sep 27, 2009 at 1:35 AM, Duy Le wrote: > Hi > >Is there any way that we can run epsilon.x if we dont have norm > conserving pseudo-potential. > I did not do any epsilon.x calculation before, and I don't understand > what's wrong with non-norm conserving potential? To calculate dielectric > constants, one needs energy and wavefunction of all states. PWscf provides > those (Kohn-Sham eigenvalues and eigen wavefunctions), and epsilon.x will do > it jobs as a post-processing. It would be nice if you or someone can explain > the problem to me. Thank you. > > >I want to run epsilon.x for YVO4 and i dont know how to use ld1.x to make > a pseudo potential. Please help or advice. > http://www.quantum-espresso.org/wiki/index.php/QESB09, (Saturday 25) has > tutorial and lectrure for generating pseudo potential (video available too). > Give it a try if you really need to generate pseudo potental. > > Best, > > On Sat, Sep 26, 2009 at 3:14 AM, dev sharma wrote: > >> Hi 2 all, >> >> Is there any way that we can run epsilon.x if we dont have norm >> conserving pseudo-potential. I want to run epsilon.x for YVO4 and i dont >> know how to use ld1.x to make a pseudo potential. Please help or advice. >> >> Thanks in advance, >> Dev Sharma, >> University of Delhi, >> >> >> >> >> >> >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- > -- > Duy Le > PhD Student > Department of Physics > University of Central Florida. > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090927/c819a9bc/attachment.htm
[Pw_forum] equilibrium lattice constant determination
Dear Sreekar, Could you please clarify why, in your opinion, energy/(unit cell volume) vs (unit cell volume) should give the minimum but not energy vs (unit cell volume)? Since you are trying to find the gs lattice constant, I am assuming you consider harmonic approximation around gs lattice parameter. So You'll expect to see a parabola in energy vs volume graph, as energy is proportional to (vol-v0)^2 around equilibrium(v0). In principle if you draw energy/vol vs vol, you should see energy/vol proportional to vol+v0^2/vol, which I think should still have a minimum.But why would you do that, since you are looking for the configuration with minimum energy? If this doesnt satisfy you, you can always use an equation of state fitting. Thats is my understanding of the issue, I'd be more than glad if somebody corrects me. emine kucukbenli, Sissa, Italy SISSA Webmail https://webmail.sissa.it/ Powered by Horde http://www.horde.org/
