Dear Mahmoud Payami,
Thank you for your answer. It helps me a lot.
So, I can use the Fixed occupation and, if the energy levels show a
small bandgap, I introduce the Smearing. Is it right?
About the second question. I've read that the result of HOMO - LUMO,
obtained after the SCF calculation, can give the bandgap. Can I obtain
the bandgap in that way? If yes, I just have to add the nbnd function in
the input file?
On 11/1/21 02:04, Mahmoud Payami Shabestari wrote:
Dear José Xavier,
Hi.
Smearing for the occupations is used when the levels near HOMO are so
close (commonly in metals near Fermi level) that in consecutive
iterations they may exchange positions and lead to nonconvergence. For
semiconductors with 3-5 eV gap I think it won't help.
Bests
Mahmoud Payami
NSTRI, AEOI, Tehran, Iran
From: José Xavier via users <[email protected]>
To: "[email protected]"
<[email protected]>
Date: Mon, 1 Nov 2021 00:18:55 +0000 (UTC)
Subject: [QE-users] occupation in biological molecules and band gap
Dear all,
I'm new in QE. The group that I'm working with usually calculates
the properties of biologically relevant molecules, like amino
acids, hormones, neurotransmitters, and drugs, and I would like to
introduce the QE code to the group. Their previous papers have
shown that the bandgap of these crystals is something between 3-5
eV, which I understand to be in the semiconductor range.
I've watched/read some tutorials about QE, and some of these
showed that the occupation of semiconductors should be "smearing",
other ones that it should be "fixed", but no one showed
calculations with this kind of molecules. What value should I use
for the SCF and electronic calculations of the crystals that I'm
going to work on (amino acids, hormones, neurotransmitters, and
drugs)?
*Are there any differences when the molecule has a metal, like the
Heme group?
Besides, I would like to ask if there is a calculation that I
could perform to obtain the bandgap of these molecules. Is it only
possible if I create the band structure figure and calculate the
difference between the peaks in VB and CB?
Thank you for your help,
Sincerely,
José Xavier
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu
<http://www.max-centre.eu>)
users mailing list [email protected]
<mailto:users%40lists.quantum-espresso.org>
https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
