<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=""><div class="">Dear Giovanni, Lorenzo and Quantum Espresso friends,</div><div class=""><br class=""></div><div class="">Thank you for your responses. It is very much appreciated.</div><div class=""><br class=""></div><div class="">I was not aware of scan_ibrav.x or cell2ibrav.x, maybe the</div><div class="">existence of these tools can be added to the warning message:</div><div class=""><br class=""></div><div class=""><div class=""><div class=""><snip></div><div class="">...</div><div class=""> Message from routine setup:</div><div class=""> using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead</div></div><div class="">…</div><div class=""></snip></div></div><div class=""><br class=""></div><div class="">It would offer a useful hint for the user.</div><div class=""><br class=""></div><div class="">Anyway, I somehow solved the issue with the help of Giovanni. Eventually,</div><div class="">it was not very difficult, maybe trivial to most QE users. But being not very </div><div class="">much trained in crystallography, it was not immediately clear to me. </div><div class=""><br class=""></div><div class="">The only open issue is with the following message in the output. It is for</div><div class="">the same system with S_2 symmetry. So the point group is C_i.</div><div class="">I guess the find_sym routine was able to figure this out.</div><div class="">If this is the case, I would recommend to add the point group symbol to the </div><div class="">output. It makes it again much clearer.</div><div class=""><br class=""></div><div class=""><div class=""><div class=""><snip></div><div class="">...</div><div class=""> Found symmetry operation: I + ( -0.5000 0.0000 -0.0000)</div><div class=""> This is a supercell, fractional translations are disabled</div><div class=""> Message from routine find_sym:</div><div class=""> Not a group! Trying with lower acceptance parameter...</div><div class=""> Message from routine find_sym:</div><div class=""> Symmetry operations form a group</div></div><div class="">…</div><div class=""></snip></div><div class=""><br class=""></div><div class="">The last line says: "Symmetry operations form a group”.</div><div class="">Great, which group is it?</div></div><div class=""><br class=""></div><br class=""><div class="">
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<div><br class=""><blockquote type="cite" class=""><div class="">On 18 Mar 2021, at 17:39, Lorenzo Paulatto <<a href="mailto:paulatz@gmail.com" class="">paulatz@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div class="">Oddly enoughm the scan_ibrav.x little program does not work in your case (I'm fixing it), but cell2ibrav does:</div><div class=""><font style="font-family:monospace" class=""><span style="color:rgb(255, 0, 135)" class="">$</span></font><font style="font-family:monospace" class=""> PW/tools/cell2ibrav.x </font></div><div class=""><font style="font-family:monospace" class="">Enter the lattice vectors (one per line)</font></div><div class=""><font style="font-family:monospace" class="">1.000000 0.000000 0.000000</font></div><div class=""><font style="font-family:monospace" class="">0.000000 1.500000 0.000000</font></div><div class=""><font style="font-family:monospace" class="">0.000000 0.000000 4.596194</font></div><div class=""><font style="font-family:monospace" class="">Enter alat (or 'x' to skip if axis are in bohr)</font></div><div class=""><font style="font-family:monospace" class="">10.627880</font></div><div class=""><font style="font-family:monospace" class="">ibrav = 8</font></div><div class=""><font style="font-family:monospace" class="">celldm(1) = 10.62788000</font></div><div class=""><font style="font-family:monospace" class="">celldm(2) = 1.50000000</font></div><div class=""><font style="font-family:monospace" class="">celldm(3) = 4.59619400</font></div><div class=""><font style="font-family:monospace" class="">New lattice vectors in bohr:</font></div><div class=""><font style="font-family:monospace" class=""> 10.62788000 0.00000000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 15.94182000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 0.00000000 48.84779829</font></div><div class=""><font style="font-family:monospace" class="">New lattice vectors in old alat:</font></div><div class=""><font style="font-family:monospace" class=""> 1.00000000 0.00000000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 1.50000000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 0.00000000 4.59619400</font></div><div class=""><font style="font-family:monospace" class="">New lattice vectors in new alat:</font></div><div class=""><font style="font-family:monospace" class=""> 1.00000000 0.00000000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 1.50000000 0.00000000</font></div><div class=""><font style="font-family:monospace" class=""> 0.00000000 0.00000000 4.59619400</font></div><div class=""><font style="font-family:monospace" class="">Discrepancy old/new in bohr = 0.000000</font></div><br class=""><div class=""><signature id="local-80497166-1ed1" class="">--<br class=""><span style="font-size:0.9em;color:gray;" class="">Lorenzo Paulatto - Paris<span class=""></span></span></signature></div><div class="gmail_quote_attribution">On Mar 18 2021, at 10:03 am, Offermans Willem <<a href="mailto:willem.offermans@vito.be" class="">willem.offermans@vito.be</a>> wrote:</div><blockquote class=""><div class=""><div class=""><br class=""></div><div class="">Dear Quantum Espresso friends,</div><div class=""><br class=""></div><div class="">In most of my calculations, I’m dealing with metallic slabs, representing</div><div class="">surfaces, derived from fcc metals, such as (221) or (533).</div><div class=""><br class=""></div><div class="">In these calculations, I’m dealing with structures with symmetry.</div><div class="">The single symmetry element is an inversion center. S_2 is the Schönfließ symbol,</div><div class="">if I recall correctly. </div><div class=""><br class=""></div><div class="">In the output file of pw.x, I encounter the following note:</div><div class=""><br class=""></div><div class=""><snip></div><div class="">...</div><div class=""> Message from routine setup:</div><div class=""> using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead</div></div><div class="">…</div><div class=""></snip></div><div class=""><br class=""></div><div class=""><div class="">The unitcell is defined as:</div><div class=""><br class=""></div><div class=""><snip></div><div class="">...</div><div class=""> celldm(1)= 10.627880 celldm(2)= 0.000000 celldm(3)= 0.000000</div><div class=""> celldm(4)= 0.000000 celldm(5)= 0.000000 celldm(6)= 0.000000</div><div class=""><br class=""></div><div class=""> crystal axes: (cart. coord. in units of alat)</div><div class=""> a(1) = ( 1.000000 0.000000 0.000000 ) </div><div class=""> a(2) = ( 0.000000 1.500000 0.000000 ) </div><div class=""> a(3) = ( 0.000000 0.000000 4.596194 ) </div></div><div class="">…</div><div class=""></snip></div><div class=""><br class=""></div><div class="">I would like to follow the advice to use the correct ibrav, but I need some help</div><div class="">to determine the correct ibrav. </div><div class=""><br class=""></div><div class="">Can someone help me to determine the correct Ibrav?</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><br class=""><div class=""><div class=""><div class=""><div class=""><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">Met vriendelijke groeten,</font></font></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">Mit freundlichen Grüßen,</font></font></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">With kind regards,</font></font></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">Willem Offermans</font></font></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">Researcher Electrocatalysis SCT</font></font></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">VITO NV | Boeretang 200 | 2400 Mol</font></font></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class="">Phone:+32(0)14335263 Mobile:+32(0)492182073 </font></font></div><div class=""><br class=""></div><div class=""><font style="font-size:12px" class=""><font style="font-family:Helvetica" class=""><a href="https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Flink.getmailspring.com%2Flink%2F2AD46120-DDAD-4F73-91B7-A26C8881CEA0%40getmailspring.com%2F0%3Fredirect%3Dmailto%253AWillem.Offermans%2540Vito.be%26recipient%3DdXNlcnNAbGlzdHMucXVhbnR1bS1lc3ByZXNzby5vcmc%253D&data=04%7C01%7C%7C0ede0550f7e64c0f1cb908d8ea2c6ed8%7C9e2777ed82374ab992782c144d6f6da3%7C0%7C1%7C637516823855682964%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=Lb1wEO%2FKzG2MuJSR0cu%2BfNjiZOLWaKOa%2F4i%2BkQ6528w%3D&reserved=0" originalsrc="https://link.getmailspring.com/link/2AD46120-DDAD-4F73-91B7-A26C8881CEA0@getmailspring.com/0?redirect=mailto%3AWillem.Offermans%40Vito.be&recipient=dXNlcnNAbGlzdHMucXVhbnR1bS1lc3ByZXNzby5vcmc%3D" shash="OhJek1znuQAi2pNnimp2f6ErkGEPIOeqxW1I1krssvELGh+UhBObngdYNRDw+p0qOlPYGY36nsK8jscl95K083756c6d4OotEQFMokbIZ/yN5k+/ltlQU8yGdQe7e76+mS7w1cvI2T7fRObJD6Mhg/XqUL/4x1O3RHbrNAPRtN4=" title="mailto:Willem.Offermans@Vito.be" class="">Willem.Offermans@Vito.be</a></font></font></div></div></div></div><br class=""></div><br class=""><div class="">_______________________________________________</div><div class="">Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu" class="">www.max-centre.eu</a>)</div><div class="">users mailing list <a href="mailto:users@lists.quantum-espresso.org" class="">users@lists.quantum-espresso.org</a></div><div class=""><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" class="">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div></blockquote><img class="mailspring-open" alt="Sent from Mailspring" width="0" height="0" style="border:0; 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