[Pw_forum] Work function calculation of CNT

[Tuo-Hung Hou]

Dear Hande,

After some searching in the archives, I found the unit of the potential
energy is eV not Ryd. Here is the link:

http://www.democritos.it/pipermail/pw_forum/2006-August/004785.html

Also based on the suggestion from Prof. Marzari, I found the calculation
makes more sense with a larger unit cell. At least a 40 Bohr hexagonal unit
cell may be required for a (8,0) tube. 

Thanks for all your inputs

Tuo-Hung

-----Original Message-----
From: pw_forum-admin at pwscf.org [mailto:pw_forum-admin at pwscf.org] On Behalf
Of Hande Ustunel
Sent: Friday, April 20, 2007 3:00 AM
To: pw_forum at pwscf.org
Subject: Re: [Pw_forum] Work function calculation of CNT

Dear Tuo-Hung,

> However, I am running into a problem that the Fermi energy from scf (1.65
> ev) is higher than any potential inside the entire supercell (ranging from
> -10.4 to 0.4 eV).  When I looked at both the charge and potential
profiles,
> they seemed to suggest the Fermi energy should be somewhere around -4 eV,
> which is not even close to the value scf reported. I am very confused now.
> What is the Fermi energy I can use? Any thoughts on this? 

You might also want to double-check the units. The Fermi energy is
reported in the output in eV whereas the potential values are in Ryd
unless I'm mistaken.

Hande

-- 
Hande Ustunel
Department of Physics
Office 439
Middle East Technical University
Ankara 06531, Turkey
Tel : +90 312 210 3264
http://www.physics.metu.edu.tr/~hande

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