<div dir="ltr"><div dir="ltr"><div>Dear Ronald,</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div>Thank you so much for your help. What you write makes perfect sense. However, I am still stymied by the example, as it seems to include two exchanges and two correlations.</div><div>XC_GGA_X_RPW86 includes both exchange and correlations</div></div></blockquote><div><br></div><div>Please, feel free to ignore the leading XC_. Only the _X_ or _C_ in the middle of the value specify exchange or correlation, respectively. You can find all the available functionals (be it exchange, correlation, or both) here: <br></div><div><a href="https://tddft.org/programs/libxc/functionals/">https://tddft.org/programs/libxc/functionals/</a><br></div><div><br></div><div>You can run the exact same calculation leaving out the leading XC_ in your functional specifications. I am not entirely sure why it is like this, probably some holdover from an older version of LibXC or CP2K? Nevertheless, I hope this clears up the issue.<br></div><div><br></div><div>Yours sincerely</div><div>Patrick Gono<br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, 12 Feb 2019 at 18:39, Ronald Cohen <<a href="mailto:reco...@gmail.com">reco...@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;">Dear Patrick Gono,<div><br></div><div>Thank you so much for your help. What you write makes perfect sense. However, I am still stymied by the example, as it seems to include two exchanges and two correlations.</div><div>XC_GGA_X_RPW86 includes both exchange and correlations</div><div>and so does VWN.</div><div>So what does the code do? It seems, at least in the energy, to ADD GGA and LDA xc (both x and c), </div><div>and that is certainly not what is wanted.</div><div><br></div><div>There is also the issue of using pseudopotentials that correspond to the xc for the bands.There are limitless combinations of XC possible, but only a few are represented in the cp2k pseudopotentials/\</div><div><br></div><div>Sincerely,</div><div><br></div><div>Ron</div><div><br></div><div><br></div><div><blockquote type="cite"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&XC</p></div></div></blockquote></div></blockquote><blockquote type="cite"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&XC_FUNCTIONAL NO_SHORTCUT</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&LIBXC T</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">FUNCTIONAL XC_GGA_X_RPW86</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END LIBXC </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&VWN T </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END VWN</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END XC_FUNCTIONAL &VDW_POTENTIAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">POTENTIAL_TYPE NON_LOCAL &NON_LOCAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">TYPE LMKLL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">VERBOSE_OUTPUT T KERNEL_FILE_NAME ./vdW_kernel_table.dat CUTOFF 160</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END NON_LOCAL &END VDW_POTENTIAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END XC</p></div></div></blockquote></div></blockquote><div> <div style="color:rgb(0,0,0);font-family:Helvetica;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-variant-east-asian:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">---<br>Ron Cohen<br><a href="mailto:reco...@gmail.com" target="_blank">reco...@gmail.com</a><br>skypename: ronaldcohen</div><div style="color:rgb(0,0,0);font-family:Helvetica;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-variant-east-asian:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">twitter: @recohen3<br><div><br></div></div><br class="gmail-m_-6384158522908317569Apple-interchange-newline"><br class="gmail-m_-6384158522908317569Apple-interchange-newline"> </div> <div><br><blockquote type="cite"><div>On Feb 12, 2019, at 6:12 PM, Patrick Gono <<a href="mailto:patric...@gmail.com" target="_blank">patric...@gmail.com</a>> wrote:</div><br class="gmail-m_-6384158522908317569Apple-interchange-newline"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Dear Ronald,</div><div><br></div><div>it is true that documentation can be sparse. I suggest following the articles cited in the manual for more information.</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">I note some related problems with the documentation. I find examples like for LIBXC:</p><div> <br class="gmail-m_-6384158522908317569webkit-block-placeholder"></div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">FUNCTIONAL XC_MGGA_X_M06_L XC_MGGA_C_M06_L</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">but the docs at </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">say</p><ul class="gmail-m_-6384158522908317569gmail-m_457967070791147240disc" style="font-family:Times;font-size:inherit"><li style="margin-left:0em;padding-left:0em;text-indent:0em"><a href="https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XC/XC_FUNCTIONAL/LIBXC.html#list_FUNCTIONAL" id="gmail-m_-6384158522908317569gmail-m_457967070791147240FUNCTIONAL" target="_blank">FUNCTIONAL</a></li><li style="margin-left:0em;padding-left:0em;text-indent:0em">This keyword cannot be repeated and it expects precisely one word.<br></li></ul><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Yet there are "two words" </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">and including VWN afterwards also seems like more than one functional, as I said above.</p></div></blockquote><div><br></div><div>In older versions (prior to 6.1), the FUNCTIONAL keyword accepted a list of words. In the newest version (6.1), this keyword only accepts a single word. Note, however, that the section &LIBXC can be repeated. So, instead of:</div><div><br></div><div>&LIBXC<br></div><div> FUNCTIONAL XC_MGGA_X_M06_L XC_MGGA_C_M06_L</div><div>&END LIBXC</div><div><br></div><div>you can do:</div><div><br></div><div><div>&LIBXC<br></div><div> FUNCTIONAL XC_MGGA_X_M06_L</div><div>&END LIBXC</div><div><div>&LIBXC<br></div><div> FUNCTIONAL XC_MGGA_C_M06_L</div><div>&END LIBXC</div><div><br></div><div>You can also mix different correlation or exchange functionals, like so:</div><div><br></div><div>&XC_FUNCTIONAL<br></div><div> &LIBXC<br> FUNCTIONAL XC_GGA_X_RPW86 <br> &END LIBXC</div><div><div> &LIBXC<br> FUNCTIONAL GGA_C_PBE<br> &END LIBX</div><div>&END XC_FUNCTIONAL<br></div><div>&vdW_POTENTIAL<br> DISPERSION_FUNCTIONAL NON_LOCAL<br> &NON_LOCAL<br> TYPE RVV10<br> PARAMETERS 9.3 0.0093<br> KERNEL_FILE_NAME ./rVV10_kernel_table.dat<br> CUTOFF 400<br> &END NON_LOCAL<br>&END vdW_POTENTIAL<br><br></div><div><br></div><br></div><div>where I used RPW86 exchange and PBE correlation. The reason behind that is that I am trying to use the (modified) rVV10 nonlocal van der Waals functional. In the original paper: <a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.87.041108" target="_blank">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.87.041108</a> the authors define the total exchange-correlation as:</div><div>XC_rVV10 = X_RPW86 + C_PW_LDA + C_non-local_vdW</div><div><br></div><div>However, in later work it was found that the non-local vdW correction from the rVV10 works quite well with other combinations of correlation and exchange functionals. Hence, I am now using<br></div></div><div>XC_rVV10 = X_RPW86 + C_PBE + C_non-local_vdW</div><div>with a specific choice of the b parameter in the vdW correction.</div><div><br></div><div>What I am trying to say is that you can mix and match the non-local vdW correction with different exchanges and correlations. The specific choice will always depend on the system you are trying to study. There are many papers testing and comparing various combinations, such as this one <a href="https://pubs.acs.org/doi/10.1021/ct4003527" target="_blank">https://pubs.acs.org/doi/10.1021/ct4003527</a> where the VV10 corrections is added to various exchanges and correlations.</div><div><br></div><div>In your input file you use the Lee-Murray-Kong-Lundqvist-Langreth (LMKLL) nonlocal van der Waals density functional (via the keyword TYPE LMKLL). If you look up the relevant publication, you will find what correlation and exchange functional it is supposed to be used with. You may also find benchmark papers that use this non-local correction on top of other-than-originally-intended exchange and correlation functionals. This allows one to choose the best combination for the system at hand (large system vs small; periodic vs isolated; metals vs semiconductors vs small molecules; etc.).</div><div><br></div><div>Hope this helps.</div><div>Yours sincerely,</div><div>Patrick Gono<br></div> </div></div></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, 12 Feb 2019 at 15:02, Ronald Cohen <<a href="mailto:reco...@gmail.com" target="_blank">reco...@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">I am quite confused about the (lack of) documentation for the XC functionals and non-local vdW. I find examples such as:<div><br></div><div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&XC</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&XC_FUNCTIONAL NO_SHORTCUT</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&LIBXC T</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">FUNCTIONAL XC_GGA_X_RPW86</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END LIBXC </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&VWN T </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END VWN</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END XC_FUNCTIONAL &VDW_POTENTIAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">POTENTIAL_TYPE NON_LOCAL &NON_LOCAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">TYPE LMKLL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">VERBOSE_OUTPUT T KERNEL_FILE_NAME ./vdW_kernel_table.dat CUTOFF 160</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END NON_LOCAL &END VDW_POTENTIAL</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">&END XC</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">(from <a href="http://archer.ac.uk/training/course-material/2014/08/CP2K/Slides/NSCCS_2014_Sanliang_Ling.pdf" style="font-family:Arial,Helvetica,sans-serif;font-size:13px" target="_blank">http://archer.ac.uk/training/course-material/2014/08/CP2K/Slides/NSCCS_2014_Sanliang_Ling.pdf</a><span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:13px"> )</span></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:13px"><br></span></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:13px">and similar even in the regtests.</span></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:13px">This seems to call both </span>XC_GGA_X_RPW86 and VWN (lda) .</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">What does it mean to call two different xc potentials in cp2k, and why would one do it?</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Tracing this in the code is not so easy either.</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Ins eom docs it seems to suggest that LDA only should be used for correlation. Is that because GGA is included </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">in the vDW function in cp2k? Also there is the question which pseudopotentials to use.</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">It seems to me that XC_GGA_X_RPW86 is correct without the VMN, and this would correapond to what is done for DF2 in</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">quantum espresso it seems.</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">I note some related problems with the documentation. I find examples like for LIBXC:</p><div> <br class="gmail-m_-6384158522908317569webkit-block-placeholder"></div><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">FUNCTIONAL XC_MGGA_X_M06_L XC_MGGA_C_M06_L</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">but the docs at </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">say</p><ul class="gmail-m_-6384158522908317569gmail-m_457967070791147240disc" style="font-family:Times;font-size:inherit"><li style="margin-left:0em;padding-left:0em;text-indent:0em"><a href="https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XC/XC_FUNCTIONAL/LIBXC.html#list_FUNCTIONAL" id="gmail-m_-6384158522908317569gmail-m_457967070791147240FUNCTIONAL" target="_blank">FUNCTIONAL</a></li><li style="margin-left:0em;padding-left:0em;text-indent:0em">This keyword cannot be repeated and it expects precisely one word.<br></li></ul><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Yet there are "two words" </p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">and including VWN afterwards also seems like more than one functional, as I said above.</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Thank you!</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1">Ronald Cohen</p><p class="gmail-m_-6384158522908317569gmail-m_457967070791147240p1"><br></p><div><span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:13px"> </span><br class="gmail-m_-6384158522908317569webkit-block-placeholder"></div> <div></div></div></div><div><br class="gmail-m_-6384158522908317569webkit-block-placeholder"></div> -- <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+uns...@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" target="_blank">https://groups.google.com/group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" target="_blank">https://groups.google.com/d/optout</a>.<br> </blockquote></div><div><br class="gmail-m_-6384158522908317569webkit-block-placeholder"></div> -- <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/_1FupbyRLPA/unsubscribe" target="_blank">https://groups.google.com/d/topic/cp2k/_1FupbyRLPA/unsubscribe</a>.<br> To unsubscribe from this group and all its topics, send an email to <a href="mailto:cp2k+uns...@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" target="_blank">https://groups.google.com/group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" target="_blank">https://groups.google.com/d/optout</a>.<br> </div></blockquote></div><br></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="mailto:cp2k+uns...@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" target="_blank">https://groups.google.com/group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" target="_blank">https://groups.google.com/d/optout</a>.<br> </blockquote></div>