<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Dear Juerg,</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">I have done further testing and may be closer to find out the source of this discrepancy. Basically, non-SCC results are "consistent" between CP2K and DFTB+. Fore SCC-DFTB, they differ in whether to include SCC at the first scf (it also seems that DFTB+ applies non-scc scf first before applying SCC energy). I don't know the coding thoughts of SCC well enough but I am wondering which one of these two is the better way. Regarding why CP2K results are sensitive to ALPHA I guess there are many local energy minimums.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Thanks, Wei</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">CP2K:</div><div class="gmail_default"><div class="gmail_default"><div class="gmail_default">Parameters<span style="white-space:pre"> </span>Li-Mulliken-charge<span style="white-space:pre"> </span>H0-energy<span style="white-space:pre"> </span>SCC-energy</div><div class="gmail_default">NonSCC full scf<span style="white-space:pre"> </span>0.737779<span style="white-space:pre"> </span> -417.18328600<span style="white-space:pre"> </span></div><div class="gmail_default">SCC-1scf<span style="white-space:pre"> </span> 0.737779<span style="white-space:pre"> </span> -355.69044000<span style="white-space:pre"> </span>0</div><div class="gmail_default">SCC-2scf<span style="white-space:pre"> </span> 0.720362<span style="white-space:pre"> </span> -361.83972460<span style="white-space:pre"> </span>0.137714872</div><div class="gmail_default"><br></div><div class="gmail_default">DFTB+:<span style="white-space:pre"> </span></div><div class="gmail_default">NonSCC full scf<span style="white-space:pre"> </span>0.737791<span style="white-space:pre"> </span> -417.18197790<span style="white-space:pre"> </span></div><div class="gmail_default">SCC-1scf<span style="white-space:pre"> </span> 0.737791<span style="white-space:pre"> </span> -417.18197790<span style="white-space:pre"> </span>10.2841704</div><div class="gmail_default">SCC-2scf<span style="white-space:pre"> </span> 0.711388<span style="white-space:pre"> </span> -417.10728727<span style="white-space:pre"> </span>9.561284596</div></div></div></div></div></div></div></div></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, Dec 19, 2018 at 9:50 AM Wei Lai <<a href="mailto:wei.w...@gmail.com">wei.w...@gmail.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 dir="ltr"><div dir="ltr"><div style="font-family:arial,helvetica,sans-serif">Dear <span style="font-family:Arial,Helvetica,sans-serif">Juerg,</span></div><div style="font-family:arial,helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif"><br></span></div><div>Thanks for your suggestion. Parameters I chose previously converged the results reasonably. To be more systematic, I tried the following combinations without specifying RCUT (I was doing that to make sure it's less than 1/2 of the box size). Comparison of these with those I presented earlier still suggests strong sensitivity to ALPHA and difference from DFTB+.</div><div><br></div><div>Thanks, Wei</div><div style="font-family:arial,helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif"><br></span></div><div><div>Accuracy<span style="white-space:pre-wrap"> </span> GMAX<span style="white-space:pre-wrap"> </span>ALPHA<span style="white-space:pre-wrap"> </span> Li-Mulliken-charge<span style="white-space:pre-wrap"> </span>H0-energy<span style="white-space:pre-wrap"> </span>SCC-energy</div><div>1.00E-06<span style="white-space:pre-wrap"> </span> 21<span style="white-space:pre-wrap"> </span>0.583<span style="white-space:pre-wrap"> </span> 0.57183<span style="white-space:pre-wrap"> </span> -414.5978042<span style="white-space:pre-wrap"> </span>8.302909355</div><div>1.00E-10<span style="white-space:pre-wrap"> </span> 21<span style="white-space:pre-wrap"> </span>0.583<span style="white-space:pre-wrap"> </span> 0.57183<span style="white-space:pre-wrap"> </span> -414.5978042<span style="white-space:pre-wrap"> </span>8.302909355</div><div>1.00E-14<span style="white-space:pre-wrap"> </span> 21<span style="white-space:pre-wrap"> </span>0.583<span style="white-space:pre-wrap"> </span> 0.57183<span style="white-space:pre-wrap"> </span> -414.5978042<span style="white-space:pre-wrap"> </span>8.302909355</div><div>1.00E-14<span style="white-space:pre-wrap"> </span> 61<span style="white-space:pre-wrap"> </span>0.583<span style="white-space:pre-wrap"> </span> 0.57183<span style="white-space:pre-wrap"> </span> -414.5978033<span style="white-space:pre-wrap"> </span>8.302910247</div><div>1.00E-14<span style="white-space:pre-wrap"> </span> 101<span style="white-space:pre-wrap"> </span>0.583<span style="white-space:pre-wrap"> </span> 0.57183<span style="white-space:pre-wrap"> </span> -414.5978027<span style="white-space:pre-wrap"> </span>8.302910732</div><div>1.00E-14<span style="white-space:pre-wrap"> </span> 101<span style="white-space:pre-wrap"> </span>0.35 (default)<span style="white-space:pre-wrap"> </span> 0.572372<span style="white-space:pre-wrap"> </span> -414.6135268<span style="white-space:pre-wrap"> </span>8.288678932</div><div><br></div></div><div><div dir="ltr" class="m_-779116430469796372gmail_signature"><div dir="ltr"><div><br></div></div></div></div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, Dec 19, 2018 at 3:41 AM <<a href="mailto:hut...@chem.uzh.ch" target="_blank">hut...@chem.uzh.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi<br> <br> the parameter in the EWALD section are not very user friendly<br> (for historical reasons). In your case you should not keep<br> RCUT at a small value and change ALPHA. <br> It is better to use the default (RCUT calculated from EWALD_ACCURACY<br> and ALPHA internally).<br> Also you have to make sure that GCUT is big enough for your system<br> to give converged values. <br> With all these settings you should see the same behaviour as in DFTB+.<br> <br> regards<br> <br> Juerg Hutter<br> --------------------------------------------------------------<br> Juerg Hutter Phone : ++41 44 635 4491<br> Institut für Chemie C FAX : ++41 44 635 6838<br> Universität Zürich E-mail: <a href="mailto:hut...@chem.uzh.ch" target="_blank">hut...@chem.uzh.ch</a><br> Winterthurerstrasse 190<br> CH-8057 Zürich, Switzerland<br> ---------------------------------------------------------------<br> <br> -----<a href="mailto:cp...@googlegroups.com" target="_blank">cp...@googlegroups.com</a> wrote: -----<br> To: "cp2k" <<a href="mailto:cp...@googlegroups.com" target="_blank">cp...@googlegroups.com</a>><br> From: "Wei Lai" <br> Sent by: <a href="mailto:cp...@googlegroups.com" target="_blank">cp...@googlegroups.com</a><br> Date: 12/19/2018 04:50AM<br> Subject: [CP2K:11061] comparing CP2K-DFTB (5.1) and DFTB+ (18.2)<br> <br> Dear CP2K users and developers,<br> <br> I was testing the DFTB functionality of CP2K and comparing it to DFTB+. I was using Li2O (324 atoms) as an example and the CP2K input file is shown in the following (without the full coordinates). <br> <br> I found CP2K-DFTB results are very sensitive to the choice of Ewald (SPME which is the only Ewald method available for DFTB) parameter (ALPHA in A^-1). For a RCUT of 6 A, an estimate of ALPHA is usually 3.5/6=0.583. These results actually suggest indeed this is a good estimate.<br> ALPHA Li-Mulliken-charge H0-energy Repulsive energy SCC-energy Tot energy<br> 0.64 0.571831 -414.5978261 1.790186269 8.302889648 -404.5047502<br> 0.583 0.57183 -414.5978042 1.790186269 8.302909311 -404.5047086<br> 0.5 0.57183 -414.5978156 1.790186269 8.302899133 -404.5047302<br> 0.35 0.572372 -414.6135268 1.790186269 8.288678932 -404.5346616<br> 0.22 0.610178 -415.6039561 1.790186269 7.126741326 -406.6870285<br> 0.219 0.611188 -415.6274692 1.790186269 7.090867312 -406.7464156<br> <br> On the other hand, DFTB+ (using Ewald instead of SPME) results are NOT very sensitive to ALPHA. I am not sure what is the unit of ALPHA in DFTB+ but I tried several values. A value of 0.219 (hand tuned) in CP2K gave similar results to those in DFTB+ with an automatic ALPHA value.<br> ALPHA Li-Mulliken-charge H0-energy Repulsive energy SCC-energy Tot energy<br> auto 0.61175023 -415.6390952 1.790189279 7.070521175 -406.7783847<br> 0.338 0.61175319 -415.6391637 1.790189279 7.07041506 -406.7785594<br> 0.64 0.6117653 -415.6394434 1.790189279 7.069981919 -406.7792722<br> 1 0.61178357 -415.6398657 1.790189279 7.069327807 -406.7803486<br> <br> I am puzzled by this comparison and wondering if you have any insight on this.<br> <br> <br> Thanks, Wei<br> <br> &GLOBAL<br> PROJECT Li2O<br> RUN_TYPE ENERGY_FORCE<br> PRINT_LEVEL LOW<br> &END GLOBAL<br> <br> &FORCE_EVAL<br> STRESS_TENSOR ANALYTICAL<br> METHOD QS<br> &DFT <br> &QS<br> METHOD DFTB<br> &DFTB<br> SELF_CONSISTENT T<br> DO_EWALD T<br> DISPERSION F<br> &PARAMETER<br> SK_FILE Li Li ./Li-Li.skf<br> SK_FILE Li O ./Li-O.skf<br> SK_FILE O Li ./O-Li.skf<br> SK_FILE O O ./O-O.skf<br> &END PARAMETER<br> &END DFTB <br> EPS_DEFAULT 1.0E-12<br> EXTRAPOLATION ASPC<br> EXTRAPOLATION_ORDER 2<br> &END QS<br> <br> &SCF <br> SCF_GUESS RESTART ! can be used to RESTART an interrupted calculation<br> MAX_SCF 100<br> EPS_SCF 1.0E-7<br> ADDED_MOS 216<br> CHOLESKY INVERSE<br> &SMEAR ON<br> METHOD FERMI_DIRAC<br> ELECTRONIC_TEMPERATURE [K] 300<br> &END SMEAR <br> &MIXING<br> METHOD DIRECT_P_MIXING<br> ALPHA 0.1<br> &END<br> &END SCF<br> <br> &POISSON<br> PERIODIC XYZ <br> &EWALD<br> EWALD_TYPE SPME<br> ALPHA .64<br> GMAX 21<br> RCUT 5<br> &END EWALD <br> &END<br> &END DFT<br> <br> &SUBSYS<br> &CELL<br> PERIODIC XYZ<br> A 13.9765253067 0.0000000000 0.0000000000<br> B 0.0000000000 13.9765253067 0.0000000000<br> C 0.0000000000 0.0000000000 13.9765253067<br> &END CELL<br> <br> &COORD<br> Li 1.1647105 1.1647105 1.1647105<br> Li 1.1647105 1.1647105 5.8235526<br> Li 1.1647105 1.1647105 10.4823942 <br> -- <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="mailto:cp2k%2Bun...@googlegroups.com" target="_blank">cp2k+uns...@googlegroups.com</a>.<br> To post to this group, send email to <a href="mailto:cp...@googlegroups.com" target="_blank">cp...@googlegroups.com</a>.<br> Visit this group at <a href="https://groups.google.com/group/cp2k" rel="noreferrer" target="_blank">https://groups.google.com/group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" rel="noreferrer" target="_blank">https://groups.google.com/d/optout</a>.<br> <br> <br> -- <br> You received this message because you are subscribed to a topic in the Google Groups "cp2k" group.<br> To unsubscribe from this topic, visit <a href="https://groups.google.com/d/topic/cp2k/RfYbOq3j0DM/unsubscribe" rel="noreferrer" target="_blank">https://groups.google.com/d/topic/cp2k/RfYbOq3j0DM/unsubscribe</a>.<br> To unsubscribe from this group and all its topics, send an email to <a href="mailto:cp2k%2Bun...@googlegroups.com" target="_blank">cp2k+uns...@googlegroups.com</a>.<br> To post to this group, send email to <a href="mailto:cp...@googlegroups.com" target="_blank">cp...@googlegroups.com</a>.<br> Visit this group at <a href="https://groups.google.com/group/cp2k" rel="noreferrer" target="_blank">https://groups.google.com/group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" rel="noreferrer" target="_blank">https://groups.google.com/d/optout</a>.<br> </blockquote></div> </blockquote></div></div>