[Pw_forum] absorption spectrum &dielectric constant of turboTDDFT

[dario rocca]

Dear Manu,
You can simply extract it with the command
$ grep "S(E)" prefix.plot_chi.dat  > file_for_plot
and use your favorite program to plot it.
Best,
Dario

On Wed, Jul 20, 2016 at 10:49 AM, Manu Hegde <mhegde at uwaterloo.ca> wrote:

> Hello Dario,
>
> I have done the similar calculations, it went well, after running
> turbo_spectrum.x  Do you have any code to extract S(E) or I have to do it
> manually?
>
> Manu
> (University of Waterloo)
>
> On Tue, Jul 19, 2016 at 8:24 PM, dario rocca <roccad at gmail.com> wrote:
>
>> Dear SungHwan,
>> please refer to
>> http://arxiv.org/pdf/1402.0486.pdf
>> and
>>
>> http://urania.sissa.it/xmlui/bitstream/handle/1963/5797/turboTDDFT-CPC.pdf?sequence=1
>> for more details.
>>
>> In the output of the postprocessing chi_1_1 is the xx component of the
>> dynamical polarizability, chi_1_2 the xy component, etc.
>> Often chi is indicated as \alpha in the papers.
>> Specifically you would have
>>
>> Component      energy of the perturbation      real part of
>> chi                          imaginary
>>                       (indicated either as E or \omega)
>> chi_1_1=          0.000000000000000E+00     0.955769346791472E+01
>> 0.000000000000000E+00
>> .........
>>
>> As you correctly say the absorption spectrum is related to the imaginary
>> part of the average of chi multiplied by E (the energy E is often
>> indicated as \omega).
>> This averaged quantity is contained in S(E). Specifically S(E) is the
>> strength function defined as
>> S(E)=2m/(\pi*e^2*\hbar) * E*Im[chi(E)], where chi has been averaged over
>> the 3 spatial directions.
>> This definition is convenient because S(E) satisfies the f-sum rule.
>> So if you extract S(E) and plot it you will have the absorption spectrum.
>> Let me know if it's still not clear
>> Best,
>> Dario
>>
>>
>>
>>
>> On Tue, Jul 19, 2016 at 4:01 PM, SungHwan Choi <sunghwanchoi91 at gmail.com>
>> wrote:
>>
>>>     hi, I am a newbie for turboTDDFT. Now, I ran a simple example. It
>>> was assume. Now I have prefix.plot_chi.dat  file. then I don't know how
>>> to generate absorption spectrum from that file and dielectric constant
>>> values. As far as I understood, the absorption spectrum is related to
>>> imaginary part of average \chi value. but in the file there are 9 values
>>>          chi_1_1
>>>          chi_2_1
>>>          chi_3_1
>>>          chi_1_2
>>>          chi_2_2
>>>          chi_3_2
>>>          chi_1_3
>>>          chi_2_3
>>>          chi_3_3
>>> This is 3*3*3 tensor. how do I get an absorption spectrum and dieletric
>>> constant values? by the way S(E) means what?
>>>
>>> Sincerely
>>> Sunghwan Choi
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://pwscf.org/mailman/listinfo/pw_forum
>>>
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://pwscf.org/mailman/listinfo/pw_forum
>>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20160720/9a62dcd0/attachment.html>