[Pw_forum] fermi level

[J. D. Burton]

Dear vega,

The "Fermi energy" is the highest occupied energy, and for an insulator this
is the valence band maximum. Just plot the DOS or the bands and look for the
gap and your "Fermi energy" is at the bottom of the gap. Alternatively, for
insulators make sure you have occupations='fixed' and search your scf output
file for "highest occupied" or "lowest unoccupied". If these are not listed
you would need to run an nscf calc *using a k-point grid that samples the
complete BZ (usually the same as your scf calc, or more dense if you want)*
with an increased nbnd (larger than the number of valence electrons) so that
some conduction band levels are also calculated.

Cheers,
J. D.

************************************
J. D. Burton, Ph.D.
jlz101 at unlserve.unl.edu
University of Nebraska Lincoln
Physics and Astronomy
Office Ph. (402) 472 2499
213C Ferguson Hall
************************************
"The job of a scientist is to generate wrong ideas as fast as possible."
-- Murray Gell-Mann

-----Original Message-----
From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
Behalf Of vega
Sent: Thursday, August 14, 2008 11:51 AM
To: PWSCF Forum
Subject: Re: [Pw_forum] fermi level

Dear all,

> Fermi energy is written in output whenever it is calculated, that is in
> any scf calculations for metals.

How about the case for semi-conductors like TiO2? When calculations for TiO2
was achieved, I can't find any information about Fermi energy in my output 
file.

could anyone can help me.

vega

==============================================================
Vega Lew ( weijia liu)
PH.D Candidate in Chemical Engineering
State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China

 

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