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<p>Hi Alex,</p>
<p>If you are interested in UV absorption spectroscopy, you cannot
use the XAS LR-TDDFT method you mention. This method specifically
targets core states, and only X-ray photons could excite electrons
from these states. The typical energy of UV photons is a few eVs,
corresponding to electronic excitations from valence states. For
this, standard TDDFT is the appropriate choice. A priori, there is
nothing preventing you to run a TDDFT calculation with a strong
static electric field.</p>
<p>Best,</p>
<p>Augustin<br>
</p>
<div class="moz-cite-prefix">On 11/9/22 01:29, Alex wrote:<br>
</div>
<blockquote type="cite" cite="mid:2ffb32e3-1619-4b91-828e-00db37b64142n@googlegroups.com">
Hi all,
<div><br>
</div>
<div>I have never done excited-state QC calculations, so I'd like
your general input on the basic possibility of getting
physically relevant data in our scenario. I have looked at the
article on CP2K's XAS LR-TDDFT and I am not entirely convinced
there's a path forward. </div>
<div><br>
</div>
<div>What we have is a finite solid tip in the presence of a
strong strong (order of tens V/nm) electric field, say, along
the tip axis, exposed to a UV pulse. The ultimate goal is to
look at "the usual," i.e., maybe electron density distribution
& densities of states at the surface/beneath the surface,
both in the absence of any pulses, as well as dynamic behaviors
upon UV adsorption. In this scenario, I am not convinced that
the core-valence separation would be valid, given the
polarization under strong static E-field. The tip material is,
say, silicon or something similar.</div>
<div><br>
</div>
<div>Any comments? Thank you!</div>
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<pre class="moz-signature" cols="72">--
Augustin Bussy
Postdoctoral researcher
Hutter Group
University of Zurich</pre>
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