<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> </head> <body lang="EN-US" link="blue" vlink="purple"> <div class="WordSection1"> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Kazimieras<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">You will get that warning whenever you have more than six 2p electrons for O or two for the O 2s, though I assume that you want to have a Hubbard U correction for the Ti 3d states alone or for both Ti 3d and O 2p states. Other choices might not made much sense.<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Mulliken is known to give orbital occupations which can be slightly larger than the limit of 2l+1 (or 4l+2 for closed shell) for some cases, e.g. more than 10 d electrons for Zn. You can ignore that warning if the occupation is only slightly larger than expected. There is a print key <a href="https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/PLUS_U.html"> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/PLUS_U.html</a> which prints the occupations of the orbitals for which a U value greater zero has been assigned in the input.<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Matthias<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p> <p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> cp...@googlegroups.com <...@googlegroups.com> <b>On Behalf Of </b>kazimieras tamoliunas<br> <b>Sent:</b> Montag, 17. Juni 2019 09:46<br> <b>To:</b> cp2k <...@googlegroups.com><br> <b>Subject:</b> [CP2K:11881] DFT+U with Ti and O<o:p></o:p></span></p> <p class="MsoNormal"><o:p> </o:p></p> <div> <p class="MsoNormal">Hello,<o:p></o:p></p> <div> <p class="MsoNormal"> i'm calculating Na(+1)Ti<span style="font-size:7.5pt">2</span>(+4)(PO4)<span style="font-size:7.5pt">3</span>(-3) using DFT+U method and the system is quite big ( 108 atoms, calculating 2x2x1, so 432 atoms in total) and i'm trying to fit the U parameter. Now i'm using U for both Ti and O (obviously Ti d orbitals). However, what's less obvious is what kind of orbitals should i apply the U correction to, regarding oxygen? Whenever i apply L=0 or L=1 ( p sounds reasonable to me) it prints out a following message:<o:p></o:p></p> </div> <div> <p class="MsoNormal"><o:p> </o:p></p> </div> <div> <p class="MsoNormal">*** 04:19:11 WARNING in dft_plus_u:mulliken :: DFT+U energy contibution ***<br> *** is negative possibly due to unphysical Mulliken charges. Check your ***<br> *** input, if this warning persists or try a different method!<o:p></o:p></p> </div> <div> <p class="MsoNormal"><o:p> </o:p></p> </div> <div> <p class="MsoNormal">Now when i set L=2 for O, the warning disappears and i get a great convergence. <o:p></o:p></p> </div> <div> <p class="MsoNormal">That i do like, however, i cannot understand how this method works. I suppose i have oxygen mostly -2, therefore it should have it's 2p fully filled. From my point of view, if i want to localise the electron i should think about 3s or 2p, but certainly not 3d orbital. Can somebody help me with that?<o:p></o:p></p> </div> <div> <p class="MsoNormal">Appreciate any help, comments or possible literature from the ones familiar with the problem!<o:p></o:p></p> </div> <div> <p class="MsoNormal"><o:p> </o:p></p> </div> <div> <p class="MsoNormal">PS. i know that these oxidation states are not correct and you cannot precisely have them in a periodic system. However, i suppose, that DFT+U method is used for certain electron localisation, therefore, i feel that they provide some ground to rely upon. Correct me if i'm mistaken!!<o:p></o:p></p> </div> <div> <p class="MsoNormal"><o:p> </o:p></p> </div> <div> <p class="MsoNormal">Regards,<o:p></o:p></p> </div> <div> <p class="MsoNormal">Kazimieras<o:p></o:p></p> </div> </div> <p class="MsoNormal">-- <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+unsu...@googlegroups.com">cp2k+unsu...@googlegroups.com</a>.<br> To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>.<br> Visit this group at <a href="https://groups.google.com/group/cp2k">https://groups.google.com/group/cp2k</a>.<br> To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/b28294d2-0f39-4676-80b7-9c48bb0d1871%40googlegroups.com?utm_medium=email&utm_source=footer"> https://groups.google.com/d/msgid/cp2k/b28294d2-0f39-4676-80b7-9c48bb0d1871%40googlegroups.com</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout">https://groups.google.com/d/optout</a>.<o:p></o:p></p> </div> </body> </html>