[Wien] Questions on the quantitative understanding of DOS and partial DOS

[J. K. Balamurugan]

Dear Lee and David,

Thanks for your quick answers. They were really helpful to me. I wish I
should read more on this topic.

With kind regards
K. Balamurugan

On Thu, Mar 22, 2012 at 12:47 PM, David Tompsett <dat36 at cam.ac.uk> wrote:

> Dear Balamurugan,
>
> Some answers below and many previous postings:
>
> On Thu, Mar 22, 2012 at 4:24 PM, J. K. Balamurugan <
> albertbalagan at gmail.com> wrote:
>
>> Dear WIEN2k developers and users,
>>
>> I have some problem in quantitative understanding the DOS and partial DOS
>> plots/data. I post the question with a case assumption of room temperature
>> (RT) structure of BaTiO3. As it is well known BaTiO3 has tetragonal
>> structure at RT. Now, Ba and Ti has one site and O has two sites. If the
>> DOS & partial DOS are calculated for BaTiO3, I will get total DOS for the
>> unit cell which contains one formula unit of BaTiO3. I will also get
>> partial DOS of Ba, Ti and O1 and O2 (in terms of total and from individual
>> orbital contribution like s, p and d whichever are applicable.) Here are my
>> questions:
>>
>> 1. Will the sum of total DOS individual atoms [i.e., total DOS of (Ba +
>> Ti + O1 + O2)] be exactly equal to total DOS of the unit cell? If the
>> answer is No, why?
>>
> No, the interstitial states contribution is missing. Only the area inside
> the muffin tin is included in the partial DOS.
>
>>
>> 2. Will the total DOS of any specific atom, say Ti, will be exactly equal
>> to the sum of orbital contributions [i.e., partial DOS of (Ti-s + Ti-p +
>> Ti-d)]?  If the answer is No, why?
>>
> Yes, but I think even further depending on how many l-values are in the
> basis set.
>
>>
>> Another related question: Let us assume a hypothetical structure where in
>> I have two formula units of BaTiO3 in a unit cell. That is the unit cell
>> has Ba2Ti2O6. Now the question is the following:
>> 3. Should I need to multiply 2 to the total DOS of individual atoms
>> {i.e., 2*[total DOS of (Ba + Ti + O1 + O2)]} to get the total DOS of the
>> unit cell with two formula unit? Will this sum be exactly equal to the
>> actual total DOS of the unit cell which we get as it is from the
>> calculations?
>>
> Yes. Then no not total DOS of cell, see point 1.
>
>>
>> Please explain me to clear these my questions. I wish also to get into
>> reading any material/user guide/article/document which could help me to
>> have a complete understanding on this issue.
>>
>> Thanks.
>>
>> With kind regards,
>> K. Balamurugan.
>>
>>
>> David Tompsett.
>
>>
>>
>> --
>> *K. Balamurugan
>> Pittsburgh, USA.
>> +1 412 961 5055*
>>
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>>
>>
>
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>


-- 
*K. Balamurugan
Pittsburgh, USA.
+1 412 961 5055*
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