[Pw_forum] energy of 33CNT
Nicholas E. Singh-Miller
nedward at MIT.EDU
Thu Jan 10 07:28:34 CET 2008
Hi Zhu,
The Fermi energy (and the Kohn-Sham eigenvalues for that matter) found in
the output file are referenced specifially to the potential for the
calculation. So to recover the 4~5 eV that you are expecting you need to
determine the vacuum potential.
hope that helps,
Nicholas
On Thu, 10 Jan 2008, Zhu Xi wrote:
> Hi Nicholas,
> thanks for your reply, but to my understaning, the 0.625eV fermi energy is
> wrong, it should be between -5~-4eV, I don't know why the code give such a
> fermi energy.....
>
>
> On 1/10/08, Nicholas E. Singh-Miller <nedward at mit.edu> wrote:
>>
>> Dear Zhu Xi,
>>
>> I have not run your input file, but assuming that it is correct and this
>> 0.625eV is what you read directly from the output, this Fermi energy
>> should also be correct. If you are interested in the work function of
>> the (3,3)CNT you will have to obtain the difference between a vacuum
>> potential and the Fermi energy. In short the potential in the vacuum != 0
>> due to the use of periodic boundary conditions. If you use pp.x to
>> obtain the potential remember that is is output in Rydbergs. This is all
>> discussed other times on the forum.
>>
>> best of luck,
>>
>> Nicholas
>>
>> On Thu, 10 Jan 2008, Zhu Xi wrote:
>>
>>> Dear users,
>>>
>>> I run a scf calculation of (3,3)CNT, but the fermi energy is 0.652eV,
>> can
>>> anyone give some suggestion? thanks
>>>
>>>
>> ====================================================================================
>>>
>>> &control
>>> calculation='scf',
>>> PSEUDO_DIR='./',
>>> prefix='33',
>>> forc_conv_thr=1.0D-4,
>>> /
>>> &SYSTEM
>>> ibrav = 0,
>>> celldm(1)= 18.8972612499,
>>> nat = 12,
>>> ntyp = 1,
>>> ecutwfc = 40.0 ,
>>> nosym = .true. ,
>>> nbnd = 48 ,
>>> occupations= 'smearing',degauss = 0.001
>>>
>>> /
>>> &electrons
>>> conv_thr = 1.D-6,
>>> mixing_beta = 0.5D0,
>>> /
>>> CELL_PARAMETERS
>>> 1.0 0.000000000 0.000000000
>>> 0.000000000 1.0 0.000000000
>>> 0.000000000 0.000000000 0.245951
>>> ATOMIC_SPECIES
>>> C 12.00000 C.pz-vbc.UPF
>>> ATOMIC_POSITIONS (crystal)
>>> C 0.625289967 0.669611155 0.250000000
>>> C 0.487077242 0.709466388 0.250000000
>>> C 0.291384631 0.523168925 0.250000000
>>> C 0.374710033 0.330388845 0.750000000
>>> C 0.512922758 0.290533612 0.750000000
>>> C 0.708615369 0.476831075 0.750000000
>>> C 0.416429985 0.692001578 0.750000000
>>> C 0.675464001 0.616817067 0.750000000
>>> C 0.312292454 0.592869751 0.750000000
>>> C 0.583570015 0.307998422 0.250000000
>>> C 0.324535999 0.383182933 0.250000000
>>> C 0.687707546 0.407130249 0.250000000
>>> K_POINTS automatic
>>> 1 1 11 0 0 0
>>>
>>> ==================================================
>>>
>>
>> *****************************************
>> Nicholas E. Singh-Miller
>> Ph.D. Candidate
>> Prof. Marzari Group (quasiamore.mit.edu)
>> Materials Science and Engineering
>> Massachusetts Institute of Technology
>> 13-4066
>> (617)324-0372
>> *****************************************
>> _______________________________________________
>> Pw_forum mailing list
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>>
>
>
>
>
*****************************************
Nicholas E. Singh-Miller
Ph.D. Candidate
Prof. Marzari Group (quasiamore.mit.edu)
Materials Science and Engineering
Massachusetts Institute of Technology
13-4066
(617)324-0372
*****************************************
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