<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">An issue with your input is that you place the point where the external saw-tooth potential<div class="">has a discontinuity in its derivative at emaxpos = 0.5 (it is in crystal units, so because edir = 3,</div><div class="">it means that the potential depends on z and the discontinuity is at (0,0,a/2)).</div><div class="">However, the CO2 molecule is placed along the x axis at fixed y = a/2 and z = a/2. As such,</div><div class="">the discontinuity, which is unphysical since in serves to compensate the spurious dipole field that</div><div class="">would arise as a consequence of the periodic boundary conditions, is located in a region where the</div><div class="">charge density is not zero. emaxpos should be set in such a way that the discontinuity il located</div><div class="">in the vacuum, in the region where the charge density is zero or in any case very small. In your setup</div><div class="">it seems that a good choice would be emaxpos=0.</div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><br class=""></div><div class="">PS since you’re studying an isolated molecule, provided the size of your supercell is sufficiently large,</div><div class="">the eigenvalues should exhibit no dependence on k. As a consequence, in this case, a 4x4x4 sampling</div><div class="">of the Brillouin zone, should provide results equivalent to a gamma only sampling. So, you can switch to</div><div class="">KPOINTS automatic</div><div class="">1 1 1 0 0 0</div><div class="">or, even better,</div><div class="">KPOINTS gamma</div><div class="">to make your calculation faster while keeping the same accuracy.<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 27 May 2020, at 03:42, ENDALE ABEBE <<a href="mailto:endtse@gmail.com" class="">endtse@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">Dear Experts, users and all</div><div class=""><br class=""></div><div class="">
<div class="gmail-nova-o-stack__item"><span class=""><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-nova-e-text--spacing-none gmail-nova-e-text--size-m gmail-nova-e-text" style="padding-right:0px"><span class="gmail-Linkify"><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s">I found the dipoles of CO2 calculated by Quantum ESPRESSO as :</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"><br class=""></div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"> Computed dipole along edir(3) :
</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"> Elec. dipole 0.3112 Ry au, 0.7909 Debye</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"> Ion. dipole 0.8137 Ry au, 2.0683 Debye</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"> Dipole 41.9812 Ry au, 106.7055 Debye</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"> Dipole field 0.5025 Ry au, <br class=""></div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s"><br class=""></div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s">I assumed the third value is the sum of the electronic and ionic contributions.</div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s">The input and output files are attached herewith. </div><div class="gmail-nova-e-text--family-sans-serif gmail-nova-e-text--color-inherit gmail-redraft-text gmail-nova-e-text--size-m gmail-nova-e-text gmail-nova-e-text--spacing-s">Since CO2 is non-polar molecule (with polar bonds), shouldn't the total dipole moment be zero?</div></span></div></span></div>
</div><div class=""><br class="">-- <br class=""><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><span style="color:rgb(153,153,153)" class=""><span style="background-color:rgb(0,0,0)" class=""><span class=""></span></span><span style="color:rgb(0,0,255)" class="">Endale Abebe</span></span></div><div class=""><span style="color:rgb(0,0,255)" class="">Program coordinator and </span><span style="color:rgb(0,0,255)" class=""><span class=""><span style="color:rgb(0,0,255)" class="">Lecturer</span></span></span></div><div class=""><span style="color:rgb(0,0,255)" class="">Faculty of Materials Science and Engineering</span></div><div class=""><span style="color:rgb(0,0,255)" class="">Jimma Institute of Technology</span></div><div class=""><span style="color:rgb(0,0,255)" class="">Jimma University<br class=""></span></div><div class=""><span style="color:rgb(0,0,255)" class="">P.O.Box 378, Jimma, Ethiopia</span></div><div class=""><span style="color:rgb(0,0,255)" class="">Mobile: +251921381598</span><br class=""></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
<span id="cid:f_kaoooz1y0"><CO2_nscf.out></span><span id="cid:f_kaoooz281"><CO2_nscf.in></span>_______________________________________________<br class="">Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" class="">www.max-centre.eu/quantum-espresso</a>)<br class="">users mailing list <a href="mailto:users@lists.quantum-espresso.org" class="">users@lists.quantum-espresso.org</a><br class=""><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" class="">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div></blockquote></div><br class=""><div class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span style="color: rgb(0, 0, 0); letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">-- <br class=""><br class="">Giovanni Cantele, PhD</span></div><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span style="color: rgb(0, 0, 0); letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class="">CNR-SPIN<br class="">c/o Dipartimento di Fisica<br class="">Universita' di Napoli "Federico II"<br class="">Complesso Universitario M. S. Angelo - Ed. 6<br class="">Via Cintia, I-80126, Napoli, Italy</span></div><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span style="color: rgb(0, 0, 0); letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""><a href="mailto:giovanni.cantele@spin.cnr.it" class="">e-mail: giovanni.cantele@spin.cnr.it</a></span></div><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span style="color: rgb(0, 0, 0); letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""> <a href="mailto:gcantele@gmail.com" class="">gcantele@gmail.com</a><br class="">Phone: +39 081 676910<br class="">Skype contact: giocan74<br class="">Web page:<span class="Apple-converted-space"> </span></span><a href="https://sites.google.com/view/giovanni-cantele" class="">https://sites.google.com/view/giovanni-cantele</a></div></div></div></div>
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