<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><div style="direction: ltr;">Dear Ferretti</div><div style="direction: ltr;">I mean inter and intera smearings in inputpp of epsilon calculation not in inputscf. Do you mean I can set them similar kpt, Ecuts and smearing in scf input?</div><div style="direction: ltr;">Thanks</div><div style="direction: ltr;">M Pashangpour</div><div style="direction: ltr;">IIAU,Tehran,Iran</div><br>Sent from my iPhone</div><div><br>On 23 Nov 2016, at 19:56, Andrea Ferretti <<a href="mailto:andrea.ferretti@unimore.it">andrea.ferretti@unimore.it</a>> wrote:<br><br></div><blockquote type="cite"><div><span></span><br><span></span><br><span>Dear Pashangpour,</span><br><span></span><br><span>the idea is very similar to the usual kpt convergence </span><br><span>vs smearing parameter for a DOS calculation.</span><br><span></span><br><span>At variance with scf runs, here you are computing a spectral quantity </span><br><span>(the dielectric function as a function of the frequency), meaning that you </span><br><span>may need a (much) finer mesh of kpts.</span><br><span></span><br><span>In general, the larger the smearing, the lower the resolution of your </span><br><span>spectrum (in the simplest case you are replacing dirac's deltas with </span><br><span>gaussians), while the larger the kpt mesh that you use, the smaller the </span><br><span>smearing parameter can be...</span><br><span></span><br><span>I would follow a recipe like this:</span><br><span>* set the smearing and converge the spectrum wrt kpts</span><br><span>* if the accuracy of the spectrum (ie the resolution of its features) is</span><br><span> ok with you, exit(),</span><br><span> otherwise reduce the smearing parameter and iterate</span><br><span>* by reducing the smearing you should expect to converge with a denser</span><br><span> mesh of kpts (a rule of thumb could be dk * delta ~ constant, where</span><br><span> dk is the kpt grid spacing and delta the smearing parameter.. though</span><br><span> it probably depends on the system and on your requirements)</span><br><span></span><br><span>Andrea</span><br><span></span><br><span></span><br><blockquote type="cite"><span>Dear all</span><br></blockquote><blockquote type="cite"><span>How can I find suitable value of intersmear and intrasmear in epsioln calculation via epsilon.x?</span><br></blockquote><blockquote type="cite"><span>Thanks in advance</span><br></blockquote><blockquote type="cite"><span>M. Pashangpour</span><br></blockquote><blockquote type="cite"><span>PhD of physics</span><br></blockquote><blockquote type="cite"><span>IAU,Tehran,Iran</span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><blockquote type="cite"><span>Sent from my iPhone</span><br></blockquote><blockquote type="cite"><span>_______________________________________________</span><br></blockquote><blockquote type="cite"><span>Pw_forum mailing list</span><br></blockquote><blockquote type="cite"><span><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a></span><br></blockquote><blockquote type="cite"><span><a href="http://pwscf.org/mailman/listinfo/pw_forum">http://pwscf.org/mailman/listinfo/pw_forum</a></span><br></blockquote><blockquote type="cite"><span></span><br></blockquote><span></span><br><span>-- </span><br><span>Andrea Ferretti, PhD</span><br><span>S3 Center, Istituto Nanoscienze, CNR</span><br><span>via Campi 213/A, 41125, Modena, Italy</span><br><span>Tel: +39 059 2055322; Skype: andrea_ferretti</span><br><span>URL: <a href="http://www.nano.cnr.it">http://www.nano.cnr.it</a></span><br><span></span><br><span>_______________________________________________</span><br><span>Pw_forum mailing list</span><br><span><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a></span><br><span><a href="http://pwscf.org/mailman/listinfo/pw_forum">http://pwscf.org/mailman/listinfo/pw_forum</a></span><br></div></blockquote></body></html>