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<div><span></span>Dear Stefano,</div><div> The system is a semiconductor, but it is +1 charged. Pwscf forces me to set a value for degauss. I want to evaluate the <f|dVtot/dR|i>, where the |i> and |f> refer to the wavefunctions of valence band maximum (VBM) and the isolated state <span style="font-size: 10.5pt; line-height: 1.5; background-color: window;">induced by defect in the band gap, respectively. I found that the related wavefucntions change a lot when the weights (occupations) of the highest bands change. By the way, I am performing a Gamma point only calculation for a large supercell with a lattice constant exceeding 10 Angstrom.</span></div><div><span style="font-size: 10.5pt; line-height: 1.5; background-color: window;"> I believe the many quantities (such as total energy) do not change significantly when the occupations of highest states vary, because contribution from these states is relatively small than that from the rest states. So I am wondering whether it is normal that wavefunctions of highest occupied states change remarkably when the occupations of highest states vary.</span></div><div><span style="font-size: 10.5pt; line-height: 1.5; background-color: window;"><br></span></div><div><span style="font-size: 10.5pt; line-height: 1.5; background-color: window;">Best regards!</span></div><div><span style="font-size: 10.5pt; line-height: 1.5; background-color: window;">Jiqiang</span></div>
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<blockquote style="margin-top: 0px; margin-bottom: 0px; margin-left: 0.5em;"><div> </div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><div style="PADDING-RIGHT: 8px; PADDING-LEFT: 8px; FONT-SIZE: 12px;FONT-FAMILY:tahoma;COLOR:#000000; BACKGROUND: #efefef; PADDING-BOTTOM: 8px; PADDING-TOP: 8px"><div><b>From:</b> <a href="mailto:degironc@sissa.it">stefano de gironcoli</a></div><div><b>Date:</b> 2015-09-20 04:07</div><div><b>To:</b> <a href="mailto:q-e-developers@qe-forge.org">q-e-developers</a></div><div><b>Subject:</b> Re: [Q-e-developers] smearing style</div></div></div><div><div class="FoxDiv20150920100536182427">
<div class="moz-cite-prefix">Dear Jiqianq<br>
the answer to your question depends on which physical quantity
you want to calculate.<br>
Is the state you want to study spatially localized ? is it an
isolated (narrow band) in a band energy gap ? are you interested
in the shallow donor states formed by the holes at the bottom of
the conduction band of a doped semiconductor ? Or is your system a
metal ?<br>
clarifying to yourself what is the question you want to answer
will help you to figure out how to compute a physically meaningful
number. <br>
<br>
stefano<br>
<br>
On 19/09/2015 12:37, Jiqiang Li wrote:<br>
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<div><span></span>Dear <span style="font-size: 10.5pt;
line-height: 1.5; background-color: window;">Lorenzo,</span></div>
<div><span style="font-size: 10.5pt; line-height: 1.5;
background-color: window;"> For example, for a
supercell with 100 electrons, it will be of 99 electrons when
the system is +1 charged. I consider the 50th band as the
highest occupied band with half occupation.</span></div>
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background-color: window;"><br>
</span></div>
<div><span style="font-size: 10.5pt; line-height: 1.5;
background-color: window;">Jiqiang</span></div>
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<div><b>From:</b> <a moz-do-not-send="true" href="mailto:paulatz@gmail.com">Lorenzo Paulatto</a></div>
<div><b>Date:</b> 2015-09-19 18:14</div>
<div><b>To:</b> <a moz-do-not-send="true" href="mailto:q-e-developers@qe-forge.org">General
discussion list for Quantum ESPRESSO developers</a></div>
<div><b>Subject:</b> Re: [Q-e-developers] smearing style</div>
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<div>
<div>Dear Jiqiang,</div>
<div>the "highest occupied banda" are obviously defined only
for insulators, i.e. </div>
<div>there is no such thing as a highest occupied bands when
using a smearing, what </div>
<div>threshold do you use for occupied/non occupied? </div>
<div> </div>
<div>kind regards </div>
<div> </div>
<div>On Saturday, September 19, 2015 05:48:09 PM Jiqiang Li
wrote:</div>
<div>> Dear developers,</div>
<div>> I want to use the wavefunctions of highest
occupied bands in a</div>
<div>> charged system to evaluate some quantities, such as
psi_i(r) ＊psi_j(r) .</div>
<div>> However, I found that the wavefunction sensitively
depends on the degauss</div>
<div>> value. So, how to choose a suitable value for
degauss when I want to</div>
<div>> obatain a physically meaningful quantity.</div>
<div> </div>
<div>> </div>
<div>> Best regards!</div>
<div>> Jiqiang Li</div>
<div>> </div>
<div>> </div>
<div>> </div>
<div> </div>
<div>-- </div>
<div>Lorenzo Paulatto - Paris</div>
<div> </div>
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