<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">In you are dealing with asymmetric slabs, dipole correction might be important. Some adsorbates are just conceived to change the work function of a material, thus representing dipole layers added on the top of a surface. The induced dipole can make the vacuum levels in the two sides of the slab rather different <div>Giovanni <br><br><div id="AppleMailSignature">Inviato da iPhone</div><div><br>Il giorno 25 lug 2018, alle ore 20:05, Paolo Costa <<a href="mailto:paolo.costa85@gmail.com">paolo.costa85@gmail.com</a>> ha scritto:<br><br></div><blockquote type="cite"><div><div dir="ltr">Hi Giovanni,<div><br></div><div>thanks a lot for your quick reply. </div><div>I guess you are definetely right, I did not recognize such error. I will put right way the calculation of the surface allowing the relax of all the atoms. I will let you know the results.</div><div><br></div><div>By the way, do you think that the dipole correction is always necessary for adsorption studies?</div><div><br></div><div>Thanks again.</div><div><br></div><div>Paolo</div></div><div class="gmail_extra"><br><div class="gmail_quote">2018-07-25 13:21 GMT-04:00 Giovanni Cantele <span dir="ltr"><<a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">giovanni.cantele@spin.cnr.it</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word;line-break:after-white-space"><div>I cannot visualise your structures at the moment, however one first issue, concerning the adsorption energy calculation is that it seems that in the system WITOUTH</div><div>the molecule you fixed some Ti/O layers, that are instead free to relax in the adsorbed system. As such, the run with the molecule is able to lower the total energy</div><div>also by allowing those atoms (a lot!), that were fixed in the other run, to change their positions. The result is that the -0.66 Ry contain also the energy gain of</div><div>the “free” surface when you let those atoms to relax towards a lower energy configuration. So, one first check would bee to see whether the atomic positions</div><div>of those atoms changed a lot (for example I see the z of one Ti atom equal to 15.819807000 when it is fixed, and 16.095206282 when it is allowed to relax, this is a change</div><div>of ~0.3 A -> 2% of the initial coordinate, that summed over all those atoms might make a difference!).</div><div>In any case I would try to make a surface (with no molecule) run where all atoms are allowed to relax and see how much energy is gained with respect to your run.</div><div><br></div><div>I could give you more hints tomorrow, if I’m able to visualise the structures</div><div><br></div><div>Giovanni</div><br><div>
<div dir="auto" style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none;word-wrap:break-word;line-break:after-white-space"><div dir="auto" style="color:rgb(0,0,0);letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none;word-wrap:break-word;line-break:after-white-space"><div style="text-align:start;text-indent:0px;word-wrap:break-word;line-break:after-white-space"><div style="text-align:start;text-indent:0px;word-wrap:break-word;line-break:after-white-space"><span style="color:rgb(0,0,0);letter-spacing:normal;text-transform:none;white-space:normal;word-spacing:0px">-- <br><br>Giovanni Cantele, PhD</span></div><div style="text-align:start;text-indent:0px;word-wrap:break-word;line-break:after-white-space"><span style="color:rgb(0,0,0);letter-spacing:normal;text-transform:none;white-space:normal;word-spacing:0px"><br>CNR-SPIN<br>c/o Dipartimento di Fisica<br>Universita' di Napoli "Federico II"<br>Complesso Universitario M. S. Angelo - Ed. 6<br>Via Cintia, I-80126, Napoli, Italy</span></div><div style="text-align:start;text-indent:0px;word-wrap:break-word;line-break:after-white-space"><span style="color:rgb(0,0,0);letter-spacing:normal;text-transform:none;white-space:normal;word-spacing:0px"><br><a href="mailto:giovanni.cantele@spin.cnr.it" target="_blank">e-mail: giovanni.cantele@spin.cnr.it</a></span></div><div style="text-align:start;text-indent:0px;word-wrap:break-word;line-break:after-white-space"><span style="color:rgb(0,0,0);letter-spacing:normal;text-transform:none;white-space:normal;word-spacing:0px"> <a href="mailto:gcantele@gmail.com" target="_blank">gcantele@gmail.com</a><br>Phone: +39 081 676910<br>Skype contact: giocan74<br>Web page:<span class="m_2258104876940113030Apple-converted-space"> </span></span><a href="https://sites.google.com/view/giovanni-cantele" target="_blank">https://sites.google.<wbr>com/view/giovanni-cantele</a></div></div></div></div>
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<div><br><blockquote type="cite"><div>On 25 Jul 2018, at 19:07, Paolo Costa <<a href="mailto:paolo.costa85@gmail.com" target="_blank">paolo.costa85@gmail.com</a>> wrote:</div><br class="m_2258104876940113030Apple-interchange-newline"><div><div dir="auto"><div style="color:purple;font-family:sans-serif;font-size:12.8px" dir="auto"><div style="font-size:12.8px">Dear experts,</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">I got nonsense value of adsorption energy by computing 4-iodoanisole on top of TiO2 anastase surface (101). </div><div style="font-size:12.8px">By calculating : (E<font size="1">surface+anisole</font>)-E<font size="1">anisole</font>-E<font size="1">s<wbr>urface, </font>I got an adsoprtion energy of 0.66 ry (8.98 eV), which is too high. </div><div style="font-size:12.8px">Now I am trying to apply the dipole correction to see if this is the problem causing an unusual adsorption energy. </div><div style="font-size:12.8px"><br></div></div><div style="font-family:sans-serif;font-size:12.8px" dir="auto">In the following link you can find the output files:</div><div style="font-family:sans-serif;font-size:12.8px" dir="auto"><span style="font-size:12.8px"><a href="https://www.dropbox.com/sh/edijwg1kyp7gx31/AACD7Up1XIIULbJFToLNqsUra?dl=0" style="text-decoration-line:none;color:rgb(66,133,244)" target="_blank">https://www.dropbox.com/sh/<wbr>edijwg1kyp7gx31/<wbr>AACD7Up1XIIULbJFToLNqsUra?dl=0</a></span><br></div><div style="color:purple;font-family:sans-serif;font-size:12.8px" dir="auto"><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">I would be glad to receive any suggestions to understand the problem. </div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">Thanks.</div><div style="font-size:12.8px" dir="auto"><br></div><div style="font-size:12.8px" dir="auto">Paolo</div></div></div>
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