# [DFTB-Plus-User] Regarding DOS and LDOS

Gabriele Penazzi penazzi at uni-bremen.de
Fri Jan 29 10:50:21 CET 2016

```Dear Kazuma,

this doesn't help a lot, as I have no idea how your system DOS looks
like and absolute numbers do not tell me a lot. Near a singularity a
numerical error of 0.79 could be irrelevant, or if somewhere else it
could hide some bug in the way we define the DOS indexes.

Can you reproduce this problem with a minimal non-scc example? If yes,
you can provide me the input and I'll give it a look

On 01/29/2016 09:58 AM, u3129004 at edu.gifu-u.ac.jp wrote:
> Dear Dr.Gabriele,
>
> 0.79 is the difference between DOS and the sum of LDOS at a energy point
> of -3.985 . I faced the same problem at other energy, too.
>
> Sincerely yours,
> Kazuma
> ----- Original Message -----
>> Hi Kazuma,
>>
>> what is 0.79? An absolute value? An integrated quantity? The relative
>> error at an energy point? Are you by chance close to a Van Hove
>> singularity?
>>
>> Best,
>> Gabriele
>>
>>
>> On 01/29/2016 06:25 AM, u3129004 at edu.gifu-u.ac.jp wrote:
>>> Dear DFTB+ user,
>>>
>>> I calculated density of states(DOS) of the system, which consists of
> 31
>>> atoms like following:
>>>
>>>     EnergyRange [eV] = -3.985  -3.985
>>>     EnergyStep [eV] = 0.001
>>>     LDOS={
>>>           ProjectionRange=1 31
>>>     }
>>>
>>> In addition, I calculated the local density of states(LDOS) under
> the
>>> same condition like following:
>>>
>>>     EnergyRange [eV] = -3.985  -3.985
>>>     EnergyStep [eV] = 0.001
>>>     LDOS={
>>>           ProjectionRange={1 1}
>>>           ProjectionRange={2 2}
>>>           ProjectionRange={3 3}
>>>            .
>>>            .
>>>            .
>>>           ProjectionRange={31 31}
>>>         }
>>>
>>> However the sum of LDOS is not equal to the DOS. There is a little
>>> diferrent. In this this difference is about 0.79. Please tell me the
>>> reason.
>>>
>>> Thank you very much in advance,
>>> Kazuma
>>>
>>>
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>
>>>
>>
>> --
>> --
>> Dr. Gabriele Penazzi
>> BCCMS - University of Bremen
>>
>> http://www.bccms.uni-bremen.de/
>> phone: +49 (0) 421 218 62337
>> mobile: +49 (0) 151 19650383
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>>
>
>
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--
--
Dr. Gabriele Penazzi
BCCMS - University of Bremen

http://www.bccms.uni-bremen.de/