[Pw_forum] Work function calculation of CNT

[degironc]

dear 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
>  
>
if you READ the link you'll discover that the units for the "potential" 
(which is actually
an energy since it is e*V)  are  Ry.

stefano
 

>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
>
>  
>