<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: style=" font-size:="" 12pt;="" color:="" #000000"=""><div><br></div><div>Dear Stefano,</div><div><br data-mce-bogus="1"></div><div> Thank you for your explanation. It is very helpful for us.</div><div><br data-mce-bogus="1"></div><div>Regards,</div><div>Krishnendu</div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>degironc@sissa.it<br><b>To: </b>users@lists.quantum-espresso.org<br><b>Sent: </b>Thursday, November 7, 2024 3:26:55 PM<br><b>Subject: </b>Re: [QE-users] Speed of valence electrons<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><p>Dear Krishnendu,</p>
<p> the group velocity of an electron associated to a given band
is related to the derivative of the energy band w.r.t. the
k-vector, which is roughly proportional to band-width and lattice
parameters which for valence electrons do not depend strongly on
the elements involved. <br>
</p>
<p> Assuming a simple dispersion like e(k) = -A*cos(k*a) ->
v_g = 1/\hbar d e(k)/ d k = A a/ \hbar * sen(k*a) <br>
</p>
<p> so max v_g ~ A a / \hbar . if you take A ~ 5 eV and a ~ 5
\AA, then max v_g ~ 3 10^7 m/s ~ 0.1 c<br>
</p>
<p> The behavior of the electrons close to the nuclei is of course
affected by relativistic effects for heavy elements, this is why
one should use relativistic pseudopotentials. <br>
</p>
<p>stefano<br>
</p>
<div>On 07/11/24 06:57, KRISHNENDU MUKHERJEE
via users wrote:<br>
</div>
<blockquote>
<div style="font-family:'arial' , 'helvetica' , sans-serif">
<div>
<div style="font-family:'arial' , 'helvetica' , sans-serif"><br>
<div>Hello everyone,<br>
</div>
<br>
<div> Does the valence electrons (those electrons for which
the wave function is solved in Quantum Espresso) have
non-relativistic speed ?<br>
</div>
<br>
<div>Thanking you,<br>
</div>
<div>Regards,<br>
</div>
<div>Krishnendu<br>
</div>
</div>
<br>
</div>
</div>
<br>
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<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 (www.max-centre.eu)<br>users mailing list users@lists.quantum-espresso.org<br>https://lists.quantum-espresso.org/mailman/listinfo/users<br></div></div></body></html>