[Pw_forum] Not getting right Band structure
Lorenzo Paulatto
paulatto at sissa.it
Tue Jul 28 12:07:01 CEST 2009
In data 28 luglio 2009 alle ore 11:54:14, Neel Singh
<neelphysics at yahoo.in> ha scritto:
> means band gap at gamma = 0.3058-(-8.9833)= 8.2891
> which is very large ??
Not necessarily, the offset of band in a periodic system is arbitrary. You
need to know where you Fermi energy is, or which are the HOMO and LUMO of
your system to find the gap.
> 2) In the output of SCF and Bands , the output file has 4 warnings
This a very frequently asked question, please see the corresponing entry
in the manual:
http://www.pwscf.org/guide/2.1.2/html-node/node56.html
http://www.pwscf.org/guide/2.1.2/html-node/node57.html
> for this I have already increase the following quantities in the
> increments
> kinetic-energy cutoff = 40.0000 Ry to 60
> charge density cutoff = 250.0000 Ry to 400
> But still the warnings are there.
It is not a big increment of the cutoff that will solve this problem, but
a small increment or nr1, nr2 nr3
cheers, and good work
--
Lorenzo Paulatto
SISSA & DEMOCRITOS (Trieste)
phone: +39 040 3787 511
skype: paulatz
www: http://people.sissa.it/~paulatto/
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