<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt">Dear Srijan,<br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">> Thanks a lot for your helpful reply. <br>You are welcome.<br><br>>However, in practice, sometime smearing keyword needs to be used for a complicated<br>>semiconductor or insulator in order get a faster scf convergence. And hence, <br>
>it is better to identify a system is non-metal or metal by its band-gap instead of smearing <br>>keyword. <br><br>As you were interested in LO-TO splitting, in fact, I meant the Gamma point calculation only.<br><br>>In particular, phonon code in QE complain a lot if the system is a spin-polarized insulator. <br>>For example, "fixed occupations and lsda need tot_magnetization", <br>>"The phonon code with constrained magnetization is not yet available", <br><br>Yes, agree. Such kind systems still seem to be problematic. At least, to me.<br><br>> " IF (epsil.AND.lgauss) & CALL errore ('phq_readin', 'no elec. field with metals', 1)", etc. etc.<br><br>But this one is correct from the physical basics. See any good textbook on solid state physics, or review by <br>S.Baroni, , S. de Girocoli, A. Dal Corso and P. Giannozzi, Rev.Mod.Phys., 73, 515, 2001.<br><br>>At least for the
last error, I guess, it is better if we write, <br>
> " IF (epsil.AND.gap_zero) & CALL errore ('phq_readin', 'no elec. field with metals', 1)"<br>
> in place of the current existing statement. Then it will give a chance to compute \epsil also for <br>> an insulating system which uses "smearing" keyword just for faster convergence.<br><br>I am not sure, this will fix the convergence problem. Besides, see the above-mentioned comment. This prevents <br>an attempt to calculate Z* and \epsilon for metallic systems and is correct.<br><br>>For magnetic insulator, is there any further example which shows a phonon-dispersion with LO-TO splitting ? <br><br>In fact, I do not remember any such kind example. <br><br>Bests,<br>Eyvaz,<br>______________________________________<br>Departmenmt of Physics, Chemistry and Biology,<br>Linkoping University, Sweden<br>eyvaz_isaev@yahoo.com, isaev@ifm.liu.se<br><br> <br>
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