<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style id="owaParaStyle" type="text/css">P {margin-top:0;margin-bottom:0;}</style>
</head>
<body ocsi="0" fpstyle="1">
<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Dear all,<br>
<br>
I am performing my first hybrid functional calculations with PWSCF.<br>
I was trying to simulate a quite large system (24 at/unit cell volume=2082.0010 a.u.^3)<br>
on a large machine (CINECA-Fermi). The scf appears quite slow so I was trying to test the convergence of the grid density for the Fock operator, to see if I can be any faster without losing too much accuracy.<br>
Following the EXX examples I set in the &system section<br>
<br>
&system<br>
................<br>
ecutwfc = 70,<br>
ecutrho = 280,<br>
occupations = 'smearing',<br>
degauss = 0.01,<br>
input_dft='pbe0', nqx1 = 1, nqx2 = 1, nqx3 = 1,<br>
/<br>
<br>
and for the regular Monkhorst-Pack grid:<br>
<br>
/<br>
K_POINTS (automatic)<br>
3 3 3 1 1 1<br>
<br>
<br>
In the output file I obtain a Monkhorst-Pack of 42 k-points, which is fine.<br>
Anyway I was expecting to get something like<br>
<br>
EXX: grid of k+q point setup nkqs = 1<br>
<br>
since, as far as I have understood, setting all nqxs to 1 amounts to performing a q=0 calculation<br>
<br>
I get, instead:<br>
<br>
EXX: grid of k+q point setup nkqs = 42<br>
<br>
that is the grid for the Fock operator is as dense as the regular Monkhorst-Pack grid.<br>
<br>
Does all this correspond to an expected behavior of pwscf?<br>
<br>
I thank all of you for your attention,<br>
<br>
Best Regards,<br>
<br>
Roberto Gaspari,<br>
Italian Institute of Technology,<br>
Concept Lab<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
</div>
</body>
</html>