<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>Il giorno 15/mag/09, alle ore 16:29, 程迎春 ha scritto:</div><br class="Apple-interchange-newline"><blockquote type="cite"><br><br> <div class="gmail_quote"> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><br>&electrons<br>/</blockquote> <div>In the scf calculation, the default convergence threshold for scf conv_thr is 1.D-6, but in the phonon calculation, the threshold </div> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"> tr2_ph=1.0d-12,<br>is much tighter !!!</blockquote></div></blockquote><div><br></div><div>Actually the converge thresholds for pw.x (conv_thr) and ph.x (tr2_ph) are not referred to the same quantity. The first is about the estimated error on the total energy, while the second is a sort of norm of the difference between the scf potential at two consecutive steps of the scf cycle (though I'm not completely sure).</div><br><blockquote type="cite"><br>I think you can increase the scf threshold and decrease the phonon threshold. You can change the both threshold to 1.D-8.</blockquote><div><br></div><div><br></div>In order to get good phonons it is usually better to have a well converged scf potential, so that it is good advice to decrease conv_thr down to 1.d-8.</div><div>However, to my knowledge, it is better not to increase tr2_ph with respect to the default (1.d-12).</div><div><br></div><div>GS</div><div><br><blockquote type="cite"> <br clear="all"> <div></div><br>-- <br>Y. C. Cheng<br>Department of Physics<br>Nanjing University<br>Nanjing 210093<br>P. R. China<br>Tel: 86-25-83592907<br>Email: <a href="mailto:yccheng.nju@gmail.com">yccheng.nju@gmail.com</a><br> _______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://www.democritos.it/mailman/listinfo/pw_forum<br></blockquote></div><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><i><br class="Apple-interchange-newline"><br class="Apple-interchange-newline"><font class="Apple-style-span" color="#7E7E7E">Gabriele Sclauzero, PhD Student</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> SISSA & CNR-INFM Democritos,</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> via Beirut 2-4, 34014 Trieste (Italy)</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> email: <a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a> </font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> phone: +39 040 3787 511</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> skype: gurlonotturno</font></i></div><div><br></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div><br></body></html>