Dear Matthias, <br /><br />I really appreciate your patience in responding to my question point by point.<br /><br />I researched the literature and saw no published EOS results for FeO using cp2k. <br /><br />I finally found that it was the VDW_POTENTIAL that led<span style="font-size: 14.6667px;"> to the significant discontinuity in my EOS curve. After eliminating the VDW_POTENTIAL potential in all my test codes, CP2K provides</span><span style="font-size: 14.6667px;"> a continuous EOS curve that is quite normal. Please see the attached figure.<br /></span><br />I never expected that <span style="font-size: 14.6667px;">VDW_POTENTIAL might have such an apparent lousy effect on the FeO structure. What do you think might be the possible fundamental mechanism for this issue? As I want to simulate the reaction between FeO surface and H2/H2O in the future, I think it might be necessary to include </span><span style="font-size: 14.6667px;">VDW_POTENTIAL.<br /></span><br />Could you please provide your opinion regarding whether including VDW_POTENTIAL in my future calculations is necessary?<br /><br />Thanks a lot.<br /><br />Best,<br />Kejiang<br /><img alt="vdw2.png" width="1046px" height="682px" src="cid:e91b0851-c9b8-4b72-ab97-f16fac2fda69" /><br /><div><div dir="auto">On Thursday, November 23, 2023 at 11:41:34 PM UTC+8 Krack Matthias wrote:<br /></div><blockquote style="margin: 0px 0px 0px 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div lang="en-CH" style="overflow-wrap: break-word;"> <div> <div> <div> <p style="margin-bottom: 12pt;"><span lang="EN-US" style="font-size: 11pt;">Dear Kejiang<u></u><u></u></span></p></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div> <ul style="margin-top: 0cm;" type="disc"> <li style="margin-bottom: 12pt; margin-left: 0cm;"> <span style="font-size: 11pt;">1. You didn't set the VDW_POTENTIAL. Don't we need to consider VDW_POTENTIAL for FeO?<u></u><u></u></span></li></ul> </div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><p style="margin-bottom: 12pt;"><span lang="EN-US" style="font-size: 11pt;">Not sure if that is needed for bulk FeO. Did you check the work of other authors? Did they apply such a vdW correction for bulk FeO?<u></u><u></u></span></p></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div> <ul style="margin-top: 0cm;" type="disc"> <li style="margin-bottom: 12pt; margin-left: 0cm;"> <span style="font-size: 11pt;">2. You didn't set the initial value for MAGNETIZATION. Is this also not necessary for FeO?<u></u><u></u></span></li></ul> </div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><p style="margin-bottom: 12pt;"><span lang="EN-US" style="font-size: 11pt;">The &BS section does the same, i.e. sets the initial on-site electronic configuration for the iron atoms, and it allows for a more detailed control.<u></u><u></u></span></p></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div> <ul style="margin-top: 0cm;" type="disc"> <li style="margin-bottom: 12pt; margin-left: 0cm;"> <span style="font-size: 11pt;">3. You didn't set the UKS and MULTIPLICITY. Is the default setting for UKS and MULTIPLICITY enough for FeO?<u></u><u></u></span></li></ul> </div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><p style="margin-bottom: 12pt;"><span lang="EN-US" style="font-size: 11pt;">Yes, it is for AFM FeO as I already explained.<u></u><u></u></span></p> <p style="margin-bottom: 12pt;"><span lang="EN-US" style="font-size: 11pt;">Matthias<u></u><u></u></span></p> <div></div></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><div> <div> <p style="margin-left: 36pt;"><span style="font-size: 11pt;">On Thursday, November 23, 2023 at 5:39:55 PM UTC+8 Krack Matthias wrote:<u></u><u></u></span></p> </div> </div></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><div><blockquote style="border-top: none; border-right: none; border-bottom: none; border-image: initial; border-left: 1pt solid rgb(204, 204, 204); padding: 0cm 0cm 0cm 6pt; margin-left: 4.8pt; margin-right: 0cm;"> <div> <div> <p style="margin-left: 36pt;"> <span lang="DE-CH" style="font-size: 11pt;">Dear Kejiang</span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="DE-CH" style="font-size: 11pt;"> </span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;">I have added a <a href="https://www.cp2k.org/howto:dft_u" target="_blank" rel="nofollow"> howto page</a> to the CP2K wiki for DFT+U calculations with an EOS calculation for cubic FeO as an example.</span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;"> </span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;">HTH</span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;"> </span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;">Matthias</span><span style="font-size: 11pt;"><u></u><u></u></span></p> <p style="margin-left: 36pt;"> <span lang="EN-US" style="font-size: 11pt;"> </span><span style="font-size: 11pt;"><u></u><u></u></span></p> </div> </div> <div> <div> <div> <div> <div style="border-right: none; border-bottom: none; border-left: none; border-image: initial; border-top: 1pt solid rgb(181, 196, 223); padding: 3pt 0cm 0cm;"> <p style="margin-bottom: 12pt; margin-left: 72pt;"> <b><span style="font-size: 12pt; font-family: Aptos, sans-serif; color: black;">From: </span></b><span style="font-size: 12pt; font-family: Aptos, sans-serif; color: black;"><span><a href="" rel="nofollow">cp...@googlegroups.com</a></span> <<span><a href="" rel="nofollow">cp...@googlegroups.com</a></span>> on behalf of Kejiang Li <<span><a href="" rel="nofollow">lyam_...@126.com</a></span>><br /> <b>Date: </b>Wednesday, 22 November 2023 at 07:19<br /> <b>To: </b>cp2k <<span><a href="" rel="nofollow">cp...@googlegroups.com</a></span>><br /> <b>Subject: </b>[CP2K:19547] Re: Significant discontinuity in EOS curver for FeO</span><span style="font-size: 11pt;"><u></u><u></u></span></p> </div> </div> </div> </div> </div> <div> <div> <div> <div> <p style="margin-bottom: 12pt; margin-left: 72pt;"> <span style="font-size: 11pt;">Dear all, <br /> <br /> Here, I also attached the test results with different sizes of supercells. There is still a sharp decrease or discontinuity on the left side of the lowest point.<br /> <br /> Could anyone provide any guidance?<br /> <br /> Thanks a lot.<br /> <br /> Best regards,<u></u><u></u></span></p> </div> </div> </div> </div> <div> <div> <div> <div> <p style="margin-bottom: 12pt; margin-left: 72pt;"> <span style="font-size: 11pt;">Kejiang<img border="0" width="1503" height="449" style="width: 15.6562in; min-height: 4.677in;" src="https://groups.google.com/group/cp2k/attach/c32459892868/cell.jpg?part=0.1&view=1" /><u></u><u></u></span></p> </div> </div> </div> </div> <div> <div> <div> <div> <div> <div> <p style="margin-left: 72pt;"> <span style="font-size: 11pt;">On Monday, November 20, 2023 at 9:00:11 AM UTC+8 Kejiang Li wrote:<u></u><u></u></span></p> </div> </div> </div> </div> </div> </div> <div> <div> <div> <div> <div> <blockquote style="border-top: none; border-right: none; border-bottom: none; border-image: initial; border-left: 1pt solid rgb(204, 204, 204); padding: 0cm 0cm 0cm 6pt; margin: 5pt 0cm 5pt 4.8pt;"> <div> <p style="margin-bottom: 12pt; margin-left: 72pt;"> <span style="font-size: 11pt;">Dear CP2K community,<br /> <br /> I am calculating the EOS for FeO with a 2*2*2 supercell. But there is always a significant discontinuity (sharp decrease) in the range of 4.3-4.4 angstrom lattice constant in the EOS curves, as shown in the figures below.<br /> <br /> I have done the following tests:<br /> - the convergence of the energy with different cutoffs;<br /> - using different functionals, including PBE, HSE, and SCAN;<br /> -including HSE with different HF fractions;<br /> -using different magnetization and +U settings. <br /> However, all the tests produce similar results with an apparent discontinuity (4.3-4.3 A) .<br /> <br /> This discontinuity is not observed in the Quantum Espresso results conducted by myself and in the results of literature that generally used VASP. I believe that the CP2K program might cause this problem.<br /> <br /> Can you give me more suggestions on how to do further tests?<br /> <br /> Here, I also attached one sample code I used during my tests.<br /> <br /> Thanks a lot.<br /> <br /> Best regards,<br /> Kejiang<br /> The University of Science and Technology Beijing<u></u><u></u></span></p> </div> </blockquote> </div> </div> </div> </div> </div> </blockquote></div></div></div></div></div><div lang="en-CH" style="overflow-wrap: break-word;"><div><div><div><div><blockquote style="border-top: none; border-right: none; border-bottom: none; border-image: initial; border-left: 1pt solid rgb(204, 204, 204); padding: 0cm 0cm 0cm 6pt; margin-left: 4.8pt; margin-right: 0cm;"><div> <div> <div> <div> <div> <blockquote style="border-top: none; border-right: none; border-bottom: none; border-image: initial; border-left: 1pt solid rgb(204, 204, 204); padding: 0cm 0cm 0cm 6pt; margin: 5pt 0cm 5pt 4.8pt;"> <p style="margin-left: 72pt;"> <b><span lang="EN-GB" style="font-size: 11pt; border: 1pt solid windowtext; padding: 0cm;">Error! 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