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<p>Dear Pietro, <br>
</p>
<p><br>
</p>
<p>Thank you very much. I basically just need the value, to be able
to tell how big it is. <br>
</p>
<p><br>
</p>
<p>Do I understand the basics correctly? Bold u_k^v is a matrix of
cartesian displacements of the same size as is the atom coordinate
matrix (G)? The one that ends up in the molden file? Can I travel
along the mode by making geometries of a * u + G, "a" being an
arbitrary scalar (yeah, I know it's only relevant near the
minimum). <br>
</p>
<p><br>
</p>
<p>As for the value of the reduced mass: just eyeballing it - it's
going to be in the order of magnitude of a simple algebraic
average mass of the atoms in the cell, something like 10-100 amu.
Is that physically relevant? I mean, an actual phonon lives in a
whole crystal, with ~N_Avogadro atoms vibrating. If it's not the
whole crystal vibrating but a wavepacket inside crystal - it might
as well involve any number of atoms between the whole crystal and
a few atoms. Shouldn't the respective reduced mass be in the order
of magnitude of about ~10 * N_atoms? What would be the relevant
literature for this problem?</p>
<p><br>
</p>
<p>Thank you <br>
</p>
<p><br>
</p>
<p></p>
<div class="moz-cite-prefix">On 10/14/24 14:42, Pietro Davide
Delugas wrote:<br>
</div>
<blockquote type="cite" cite="mid:AS2PR07MB95186DF028CE1BF90C6C142BAF442@AS2PR07MB9518.eurprd07.prod.outlook.com">
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<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
Hello</div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
Generally, the reduced mass of the phonon modes is not very
useful because it is implicitly included in the normalization of
their displacements, and introducing it explicitly would only
complicate things.</div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
However, one definition of the reduced mass could be:</div>
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<br>
</div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
<img id="image_0" style="width: 320px; height: 82px;" data-outlook-trace="F:1|T:1" src="cid:part1.uZQic9IP.BTgnTNhx@uwr.edu.pl" class="" width="320" height="82"></div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
Where k is the index running on all atoms, m_k is the mass, and
u_k are the displacements of the mode. </div>
<div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
<br>
</div>
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<br>
</div>
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Here are some notes <a href="https://hackmd.io/@pietrodelugas/r1SykO511l" id="LPlnk300848" class="OWAAutoLink moz-txt-link-freetext" moz-do-not-send="true">
https://hackmd.io/@pietrodelugas/r1SykO511l</a></div>
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Pietro</div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> 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
Andrii Shyichuk via users
<a class="moz-txt-link-rfc2396E" href="mailto:users@lists.quantum-espresso.org"><users@lists.quantum-espresso.org></a><br>
<b>Sent:</b> Saturday, October 12, 2024 01:21<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a>
<a class="moz-txt-link-rfc2396E" href="mailto:users@lists.quantum-espresso.org"><users@lists.quantum-espresso.org></a><br>
<b>Subject:</b> [QE-users] Reduced mass?</font>
<div> </div>
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<div class="x_PlainText">Dear Users,<br>
<br>
How do I get the reduced mass of a vibrational (phonon) mode
from (I <br>
guess) PH.X?<br>
<br>
I assume it must be calculated somewhere, but it is not
printed. It is <br>
not mentioned in the PH manual (searched for "mass") and it
looks like <br>
nobody asked it here (searched for "reduced mass").<br>
<br>
Thank you.<br>
<br>
Best regards.<br>
<br>
dr Andrii Shyichuk, Faculty of Chemistry, University of
Wrocław<br>
<br>
</div>
</font>
<p><strong><span style="color:#999; font-size:17px"><br>
</span></strong></p>
<p><strong><span style="color:#999; font-size:17px">dr Andrii
Shyichuk</span></strong><span style="color:#999; font-size:11px"><br>
ADIUNKT<br>
Zakład Chemii Nieorganicznej, Wydział Chemii<br>
<br>
</span><span style="font-size:14px; color:#999"><b>Uniwersytet
Wrocławski</b><br>
ul. F. Joliot-Curie 14<br>
50-383 Wrocław<br>
tel. +48 71 375 72 65</span></p>
<p><a href="https://uni.wroc.pl" title="" moz-do-not-send="true"><img id="x_0.6m8xscwyq8s" data-outlook-trace="F:1|T:1" src="cid:part2.BxClowrP.UKz0RWlQ@uwr.edu.pl" class="" border="0"></a><a href="https://uwr.edu.pl/inicjatywa-doskonalosci-uczelnia-badawcza/" title="" moz-do-not-send="true"><img id="x_0.nmarr8syhb9" style="font-size:1rem" data-outlook-trace="F:1|T:1" src="cid:part3.8ETV2hn4.s2r2ZhnP@uwr.edu.pl" class="" border="0"></a><img id="x_0.7ub9tblud3r" style="font-size:1rem" data-outlook-trace="F:1|T:1" src="cid:part4.flWbfyXe.WQQGAkwG@uwr.edu.pl" class="" border="0"></p>
<p><span style="color:rgb(153,153,153); font-size:8px">Wiadomość
ta oraz wszelkie załączone do niej pliki są poufne i mogą
być prawnie chronione. Jeżeli nie jest Pani/Pan zamierzonym
adresatem niniejszej wiadomości, nie może Pani/Pan jej
ujawniać, kopiować, dystrybuować ani też w żaden inny sposób
udostępniać lub wykorzystywać. O błędnym zaadresowaniu
wiadomości proszę niezwłocznie poinformować nadawcę i usunąć
wiadomość.</span><br>
</p>
</div>
</blockquote>
<p><strong><span style="COLOR: #999; FONT-SIZE: 17px"><br></span></strong></p><p><strong><span style="COLOR: #999; FONT-SIZE: 17px">dr Andrii Shyichuk</span></strong><span style="COLOR: #999; FONT-SIZE: 11px"><br>ADIUNKT<br />Zakład Chemii Nieorganicznej, Wydział Chemii<br><br></span><span style="FONT-SIZE: 14px; COLOR: #999"><b>Uniwersytet Wrocławski</b><br>ul. F. Joliot-Curie 14<br>50-383 Wrocław<br>tel. +48 71 375 72 65</span></p><p><a href="https://uni.wroc.pl" title=""><img src="cid:2022_02_uwr_arqus_pocitedostopki_bdb4c7bb-1172-4107-90f8-1b2742af358e.png" id="0.6m8xscwyq8s" border="0"></a><a href="https://uwr.edu.pl/inicjatywa-doskonalosci-uczelnia-badawcza/" title=""><img src="cid:2022_02_uwr_arqus_pocitedostopki3_e5829564-9e6b-4628-ac3b-6e1d97627e4b.png" id="0.nmarr8syhb9" style="font-size: 1rem;" border="0"></a><img src="cid:2022_02_uwr_arqus_pocitedostopki4_89c9e33b-31a4-4974-a07d-b817a789344c.png" id="0.7ub9tblud3r" style="font-size: 1rem;" border="0"></p><p><span style="color: rgb(153, 153, 153); font-size: 8px;">Wiadomość ta oraz wszelkie załączone do niej pliki są poufne i mogą być prawnie chronione. Jeżeli nie jest Pani/Pan zamierzonym adresatem niniejszej wiadomości, nie może Pani/Pan jej ujawniać, kopiować, dystrybuować ani też w żaden inny sposób udostępniać lub wykorzystywać. O błędnym zaadresowaniu wiadomości proszę niezwłocznie poinformować nadawcę i usunąć wiadomość.</span><br></p></body>
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