<div dir="ltr"><div>Dear Patrick,</div><div><br></div><div>Thank you so much for your nice and detailed answer. That helped a lot.<br></div><br>On Sunday, May 5, 2019 at 5:04:44 PM UTC+4:30, Patrick Gono wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="auto">Dear Mohammad,<div dir="auto"><br></div><div dir="auto">Do you want to perform a geometry optimization (GEO_OPT), or a cell optimization in which the cell parameters are varied as well?</div><div dir="auto"><br></div><div dir="auto">Geometry optimization is by its very nature a zero Kelvin method - after all, you are minimizing energy to find the ground state of the computational cell geometry. </div><div dir="auto"><br></div><div dir="auto">So is cell optimization by default, but you can choose the MD type, which uses (finite temperature) molecular dynamics to compute the stress tensor. The MD section with the appropriate temperature must be defined in order to use this method. But I suspect this is not really what you are after.</div><div dir="auto"><br></div><div dir="auto">Define the &GEO_OPT section and set up a GEO_OPT calculation to find the optimized structure. Alternatively, if you want to relax the cell parameters, go for CELL_OPT. The sections are quite similar, in both cases I recommend the BFGS algorithm unless tou encounter instabilities in the optimization process. You can find the appropriate tutorials on the official cp2k website, or via Google.</div><div dir="auto"><br></div><div dir="auto">Regarding the smearing: as you yourself mention your system has a gap, I would opt for a different scf method. Instead of direct diagonalization (with or without smearing) consider adopting an orbital transformation method (defined in the & OT section). These provide improved performance, although may not be as reliable as diagonalization in some cases. However, the OT methods work well for virtually any system I study. </div><div dir="auto"><br></div><div dir="auto">Regardless, you chose the fermi-dirac smearing method which takes one parameter, a temperature. This is not the real temperature of the system, it's only a parameter of the smearing method. Using 0 K basically means no smearing (the FD distribution is a step function at zero temperature). Consider commenting out the smearing section if you do not intend to use smearing.</div><div dir="auto"><br></div><div dir="auto">Yours sincerely, </div><div dir="auto">Patrick Gono</div></div><br><div class="gmail_quote"><div dir="ltr">On Sun, 5 May 2019, 08:20 Mohammad Shakiba, <<a href="javascript:" rel="nofollow" target="_blank" gdf-obfuscated-mailto="b7dumUvGAwAJ" onmousedown="this.href='javascript:';return true;" onclick="this.href='javascript:';return true;">mshakiba....@gmail.<wbr>com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hello everyone,</div><div><br></div><div>What is the way to set the temperature during geometry optimization? Also, in the manual for CELL_OPT it says "<i>This section sets the environment for the optimization
of the simulation cell. Two possible schemes are available: (1) Zero
temperature optimization; (2) Finite temperature optimization." </i>but there is no section for setting the temperature (My system is a semiconductor).<br><i></i></div><div><i><br></i></div><div>I also used Fermi-Dirac smearing function with the following inputs but that gives me an error after one scf step <b>"KS energy is an abnormal value (NaN/Inf).".</b></div><div><br></div><div><br></div><div> SCF WAVEFUNCTION OPTIMIZATION<br><br> Step Update method Time Convergence Total energy Change<br> ------------------------------<wbr>------------------------------<wbr>------------------<br> 1 P_Mix/Diag. 0.40E+00 30.0 1.31109320 -882.6554194381 -8.83E+02<br><br> *****************************<wbr>******************************<wbr>********************<br> * ___ <wbr> <wbr> *<br> * / \ <wbr> <wbr> *<br> * [ABORT] <wbr> <wbr> *<br> * \___/ KS energy is an abnormal value (NaN/Inf). *<br> * | <wbr> <wbr> *<br> * O/| <wbr> <wbr> *<br> * /| | <wbr> <wbr> *<br> * / \ <wbr> qs_ks_methods.F:866 *<br> *****************************<wbr>******************************<wbr>********************<br><br></div><div><br></div><div><br></div><div>Can any one help me in this regard? Thanks in advance.</div><div><br></div><div>The smearing input section which provides the electronic temperature:</div><div><br></div><div>&SCF<br> SCF_GUESS ATOMIC<br> MAX_SCF 300<br> EPS_SCF 1.0E-7<br> ADDED_MOS 20<br> &DIAGONALIZATION<br> ALGORITHM STANDARD<br> EPS_ADAPT 0.01<br> &END DIAGONALIZATION<br> &SMEAR ON<br> METHOD FERMI_DIRAC<br> ELECTRONIC_TEMPERATURE [K] 0<br> &END<br>&END SCF<br><i></i></div></div>
<p></p>
-- <br>
You received this message because you are subscribed to the Google Groups "cp2k" group.<br>
To unsubscribe from this group and stop receiving emails from it, send an email to <a href="javascript:" rel="nofollow" target="_blank" gdf-obfuscated-mailto="b7dumUvGAwAJ" onmousedown="this.href='javascript:';return true;" onclick="this.href='javascript:';return true;">cp...@googlegroups.<wbr>com</a>.<br>
To post to this group, send email to <a href="javascript:" rel="nofollow" target="_blank" gdf-obfuscated-mailto="b7dumUvGAwAJ" onmousedown="this.href='javascript:';return true;" onclick="this.href='javascript:';return true;">c...@googlegroups.com</a>.<br>
Visit this group at <a href="https://groups.google.com/group/cp2k" rel="nofollow" target="_blank" onmousedown="this.href='https://groups.google.com/group/cp2k';return true;" onclick="this.href='https://groups.google.com/group/cp2k';return true;">https://groups.google.com/<wbr>group/cp2k</a>.<br>
For more options, visit <a href="https://groups.google.com/d/optout" rel="nofollow" target="_blank" onmousedown="this.href='https://groups.google.com/d/optout';return true;" onclick="this.href='https://groups.google.com/d/optout';return true;">https://groups.google.com/d/<wbr>optout</a>.<br>
</blockquote></div>
</blockquote></div>