<div dir="ltr">Hello users,<br><br>I was just wondering if anyone had any inputs on this: Using a 1x1x1 q grid for HSE calculations in the case of 'large non-metallic systems'.<br>I would greatly appreciate any points or resources regarding this. <br><br><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">Sincerely,</span><br><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">Shivesh Sivakumar </span></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">Graduate Teaching Assistant<br>Materials Science and Engineering</div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">University of Washington-Seattle<br>WA-98105<br><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">(206) 474-8174</span></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jan 29, 2021 at 7:15 PM Shivesh Sivakumar <<a href="mailto:shiveshsivakumar@gmail.com">shiveshsivakumar@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">Hello users,<br><br>I was seeking a clarification in the documentation for calculation of the exact exchange in HSE calculations. Paraphrasing what's mentioned in the documentation: <br><br>Specifically, in the case of large non-metallic systems, it is reasonable that NQS can be set to 1 (where NQS = nqx1*nqx2*nqx3).<br><br>My qualms are:<br><div>1. 

I wonder how loose the definition of 'large non-metallic systems' is. 

Does it just stipulate a large enough bandgap? (Even though KS-DFT underestimates it?) <br></div><div>2. Why does the nature of the system allow us to adopt a very coarse q grid?<br><br>I would greatly appreciate any inputs on these points. <br><br><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">Sincerely,</span><br><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">Shivesh Sivakumar </span></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">Graduate Teaching Assistant<br>Materials Science and Engineering</div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">University of Washington-Seattle<br>WA-98105<br><span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;margin:0px;padding:0px;border:0px;vertical-align:baseline;color:inherit">(206) 474-8174</span></div></div></div>
_______________________________________________<br>
Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu" rel="noreferrer" target="_blank">www.max-centre.eu</a>)<br>
users mailing list <a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a><br>
<a href="https://lists.quantum-espresso.org/mailman/listinfo/users" rel="noreferrer" target="_blank">https://lists.quantum-espresso.org/mailman/listinfo/users</a></blockquote></div>