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<div class="moz-cite-prefix">Dear ZARA (or NBSH, WBR, NN ?)<br>
<br>
as mentioned in some of the other answers you need to find the
shift of the average electrostatic potential (the internal
reference of the calculation) to the vacuum level.<br>
If your system is 0 dimensional then the assume_isolated option
may be helpful.<br>
In particular the 'martyna-tuckerman' (or 'm-t' or 'mt') should
work for you.<br>
check G.J. Martyna, and M.E. Tuckerman,"A reciprocal space based
method for treating long range interactions in ab-initio and
force-field-based calculation in clusters", J.Chem.Phys. 110, 2810
(1999).<br>
The zero of the potential is set to the vacuum level so the
printed eigenvalue is directly what you want. Be careful if the
HOMO becomes positive as this indicates the state is not bound and
the correction has gone bananas.<br>
<br>
An alternative also working for different geometries is the
electrostatic embedding implemented in the environ module and
developed by Oliviero Andreussi and co-workers .<br>
(check <a class="moz-txt-link-freetext" href="http://www.quantum-environment.org/">http://www.quantum-environment.org/</a>)<br>
<br>
best<br>
<br>
stefano<br>
<br>
<br>
On 26/07/2016 17:45, ZARA NBSH wrote:<br>
</div>
<blockquote
cite="mid:CAP8ZduN72GkM1Bj=EChA_mPj+JBfAdnPhB5Vppmr9N0ijDrhUQ@mail.gmail.com"
type="cite">
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<div class="gmail_default" style="font-size:large;color:#20124d">Dear
users,</div>
<div class="gmail_default" style="font-size:large;color:#20124d">I
would like to calculate the highest occupied state energy of a
nano-structure with respect to the vacuum level.</div>
<div class="gmail_default" style="font-size:large;color:#20124d"><br>
</div>
<div class="gmail_default" style="font-size:large;color:#20124d">I
took vacuum about 20A, if I increase the vacuum the total
energy and gap do not change but the highest occupied and the
lowest occupied states will be shifted up with a same amount.</div>
<div class="gmail_default" style="font-size:large;color:#20124d">I
can't understand the meaning of this energy shift,</div>
<div class="gmail_default" style="font-size:large;color:#20124d">how
can I calculate these energy respect to the vacuum level?<br>
</div>
<div class="gmail_default" style="font-size:large;color:#20124d"><br>
</div>
<div class="gmail_default" style="font-size:large;color:#20124d">I
really appreciate your help in advance.</div>
<div class="gmail_default" style="font-size:large;color:#20124d"><br>
</div>
<div class="gmail_default" style="font-size:large;color:#20124d">WBR</div>
<div class="gmail_default" style="font-size:large;color:#20124d">-NN</div>
<div class="gmail_default" style="font-size:large;color:#20124d">Teran
uni</div>
<div class="gmail_default" style="font-size:large;color:#20124d"><br>
</div>
</div>
<br>
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