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<p>Thank you Stefano! I was actually searching for a better
reference but did not think about your Rev. Mod. Phys. which I
usually suggest to our students for reading and understanding a
bit more about DFPT. Concerning optical properties also this might
be interesting:
<a class="moz-txt-link-freetext" href="https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.74.601">https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.74.601</a><br>
</p>
<div class="moz-cite-prefix">On 8/9/23 11:30, Stefano Baroni wrote:<br>
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<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US">Hi All. Many thanks for this interesting
discussion.
<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US">Thomas: the literature you recommend (</span><span
style="font-size:11.0pt"><a
href="https://pubs.rsc.org/en/content/articlelanding/2023/CP/D2CP05991F"
moz-do-not-send="true" class="moz-txt-link-freetext">https://pubs.rsc.org/en/content/articlelanding/2023/CP/D2CP05991F</a></span><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US">) is rather ill informed. It overlooks the fact
that the problem of a proper definition of the position
operator in the calculation of dielectric and optical
properties is as old (actually older) than
density-functional perturbation theory. None of the original
literature is properly cited. A better informed reference,
with a historically accurate account of the relevant
literature is
<a
href="https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.73.515"
moz-do-not-send="true" class="moz-txt-link-freetext">https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.73.515</a><o:p></o:p></span></p>
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style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US">Best regards – SB<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:Helvetica;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span
style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">users
<a class="moz-txt-link-rfc2396E" href="mailto:users-bounces@lists.quantum-espresso.org"><users-bounces@lists.quantum-espresso.org></a> on behalf
of Thomas Brumme <a class="moz-txt-link-rfc2396E" href="mailto:tbrumme@msx.tu-dresden.de"><tbrumme@msx.tu-dresden.de></a><br>
<b>Date: </b>Wednesday, 9 August 2023 at 11:13<br>
<b>To: </b>Quantum ESPRESSO users Forum
<a class="moz-txt-link-rfc2396E" href="mailto:users@lists.quantum-espresso.org"><users@lists.quantum-espresso.org></a>, Brian de Keijzer
<a class="moz-txt-link-rfc2396E" href="mailto:briandekeyzer@hotmail.com"><briandekeyzer@hotmail.com></a><br>
<b>Subject: </b>Re: [QE-users] How does one calculate
dipole moments or access (readable) wave functions from
e.g. PW?<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt">Dear
Brian,<br>
<br>
Sorry to be a bit blunt but your question cannot be
answered in a <br>
one-liner and indicates that<br>
you might miss a few important points.<br>
<br>
I guess you have read the input description of bands.x and
since you're <br>
are still asking how to<br>
get the dipole matrix elements you are probably unaware of
the fact that <br>
those are not well<br>
defined in solids. Well, at least the position operator is
not well <br>
defined in an infinite solid<br>
because every point could be the origin. Thus, one has to
use the <br>
momentum operator instead.<br>
(see, e.g., Eq. (7) in this paper <br>
<a
href="https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.80.1800)"
moz-do-not-send="true" class="moz-txt-link-freetext">https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.80.1800)</a><br>
<br>
I suggest to read some publications first, books, in order
to understand <br>
what you need to do.<br>
This paper seems quite useful - I didn't read it carefully
though but <br>
just found it via a quick<br>
Google search:<br>
<br>
<a
href="https://pubs.rsc.org/en/content/articlelanding/2023/CP/D2CP05991F"
moz-do-not-send="true" class="moz-txt-link-freetext">https://pubs.rsc.org/en/content/articlelanding/2023/CP/D2CP05991F</a><br>
<br>
If you're interested in optical properties then there are
many more <br>
things to take into account.<br>
A good starting point might be the pages of the Yambo
code, in <br>
particular this:<br>
<br>
<a
href="https://www.yambo-code.eu/wiki/index.php/Main_Page"
moz-do-not-send="true" class="moz-txt-link-freetext">https://www.yambo-code.eu/wiki/index.php/Main_Page</a><br>
<br>
and more specifically the thesis of Andrea Marini has a
good collection <br>
of the equations and<br>
references<br>
<br>
<a
href="https://www.yambo-code.eu/wiki/images/2/20/Marini_PhD.pdf"
moz-do-not-send="true" class="moz-txt-link-freetext">https://www.yambo-code.eu/wiki/images/2/20/Marini_PhD.pdf</a><br>
<br>
In a nutshell: you need to calculate the dielectric
function and then <br>
there are different<br>
approximations involved.<br>
<br>
Kind regards<br>
<br>
Thomas<br>
<br>
On 8/9/23 09:27, Brian de Keijzer wrote:<br>
> Hi all,<br>
><br>
><br>
> Would anyone know how one retrieves the dipole matrix
elements from bands.x (or in another way?)?<br>
><br>
> Any help is appreciated.<br>
><br>
><br>
> Bests,<br>
><br>
> Brian de Keijzer<br>
><br>
>> On 25 Jul 2023, at 16:09, Brian de Keijzer
<a class="moz-txt-link-rfc2396E" href="mailto:briandekeyzer@hotmail.com"><briandekeyzer@hotmail.com></a> wrote:<br>
>><br>
>> Hi Paolo,<br>
>><br>
>> Thank you for your answer’<br>
>><br>
>> Bands.x had caught my eye before but I did not
notice how to make it output transition dipole moments.
How would one compute those?<br>
>><br>
>> Meanwhile I managed to indeed get hdf5 output.
That’s great! If there is a native way to obtain the
values I want it’s preferable tho.<br>
>><br>
>> Best regards,<br>
>><br>
>> Brian de Keijzer<br>
>><br>
>>> On 25 Jul 2023, at 13:37, Paolo Giannozzi
<a class="moz-txt-link-rfc2396E" href="mailto:paolo.giannozzi@uniud.it"><paolo.giannozzi@uniud.it></a> wrote:<br>
>>><br>
>>> I think code "bands.x" can compute dipole
matrix elements.<br>
>>><br>
>>> About direct access to wavefunctions: the
default fortran binary format is basically unreadable
except via the routines of QE. One may optionally write
hdf5 files that are much easier to read with external
utilities, though.<br>
>>><br>
>>> Paolo<br>
>>><br>
>>>> On 7/25/23 10:40, Brian de Keijzer wrote:<br>
>>>> [You don't often get email from
<a class="moz-txt-link-abbreviated" href="mailto:briandekeyzer@hotmail.com">briandekeyzer@hotmail.com</a>. Learn why this is important at
<a href="https://aka.ms/LearnAboutSenderIdentification"
moz-do-not-send="true" class="moz-txt-link-freetext">https://aka.ms/LearnAboutSenderIdentification</a>
]<br>
>>>> Hi all,<br>
>>>> New QE users here. I’ve used QE so far to
compute band structures for crystals. I am however very
much interested in calculating the dipole matrix elements
for said crystals. Does QE have a module that allows one
to do this? If so, how would that work?<br>
>>>> Moreover, I have read that it is possible
to use the wave functions directly. That would allow me to
compute the dipole elements. Unfortunately most posts that
I come across appear to be a bit dated tho. What would be
the best way to access the wave functions using more
recent versions of e.g. Python? I’ve come across postqe
but that appears to no longer be in development nor does
the installation work on my Python 3.9 distribution.<br>
>>>> Anyhow; I’m looking to learn how to
compute k-dependent transition dipole moments in QE. It
would be awesome if anyone would want to provide an
outline of how such a thing is to be done using the latest
version of QE.<br>
>>>> Bests,<br>
>>>> Brian de Keijzer<br>
>>>>
_______________________________________________<br>
>>>> The Quantum ESPRESSO community stands by
the Ukrainian<br>
>>>> people and expresses its concerns about
the devastating<br>
>>>> effects that the Russian military
offensive has on their<br>
>>>> country and on the free and peaceful
scientific, cultural,<br>
>>>> and economic cooperation amongst peoples<br>
>>>>
_______________________________________________<br>
>>>> Quantum ESPRESSO is supported by MaX (<a
href="http://www.max-centre.eu" moz-do-not-send="true">www.max-centre.eu</a>)<br>
>>>> users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br>
>>>> <a
href="https://lists.quantum-espresso.org/mailman/listinfo/users"
moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
>>> -- <br>
>>> Paolo Giannozzi, Dip. Scienze Matematiche
Informatiche e Fisiche,<br>
>>> Univ. Udine, via delle Scienze 208, 33100
Udine, Italy<br>
>>> Phone +39-0432-558216, fax +39-0432-558222<br>
> _______________________________________________<br>
> The Quantum ESPRESSO community stands by the
Ukrainian<br>
> people and expresses its concerns about the
devastating<br>
> effects that the Russian military offensive has on
their<br>
> country and on the free and peaceful scientific,
cultural,<br>
> and economic cooperation amongst peoples<br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX (<a
href="http://www.max-centre.eu" moz-do-not-send="true">www.max-centre.eu</a>)<br>
> users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br>
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moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
<br>
-- <br>
Dr. rer. nat. Thomas Brumme<br>
Theoretical chemistry<br>
TU Dresden - KOE / 103<br>
Bergstr. 66c<br>
01069 Dresden<br>
<br>
Tel: +49 (0)351 463 39449<br>
<br>
email: <a class="moz-txt-link-abbreviated" href="mailto:thomas.brumme@tu-dresden.de">thomas.brumme@tu-dresden.de</a><br>
<br>
_______________________________________________<br>
The Quantum ESPRESSO community stands by the Ukrainian<br>
people and expresses its concerns about the devastating<br>
effects that the Russian military offensive has on their<br>
country and on the free and peaceful scientific, cultural,<br>
and economic cooperation amongst peoples<br>
_______________________________________________<br>
Quantum ESPRESSO is supported by MaX (<a
href="http://www.max-centre.eu" moz-do-not-send="true">www.max-centre.eu</a>)<br>
users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br>
<a
href="https://lists.quantum-espresso.org/mailman/listinfo/users"
moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.quantum-espresso.org/mailman/listinfo/users</a><o:p></o:p></span></p>
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<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (<a class="moz-txt-link-abbreviated" href="http://www.max-centre.eu">www.max-centre.eu</a>)
users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a>
<a class="moz-txt-link-freetext" href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a></pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Dr. rer. nat. Thomas Brumme
Theoretical chemistry
TU Dresden - KOE / 103
Bergstr. 66c
01069 Dresden
Tel: +49 (0)351 463 39449
email: <a class="moz-txt-link-abbreviated" href="mailto:thomas.brumme@tu-dresden.de">thomas.brumme@tu-dresden.de</a></pre>
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