in fact , this question has been asked for many times in the forum. Just do a refined search with 'workfunction ' or '<br>vacuum level ' keywords in google or other engines will <br>help you a lot. And there is also a example about how<br>
to do workfunction's calculation supplied with QE, which <br>you can find in $QE/examples/WorkFct_example. <br><br>how to define vacuum level ? a simple or handwaving picture is to do plane average of electrostatic potential <br>
perpendicular to vacuum layer. If your vacuum layer is <br>thick enough, you should find a constant value in the vacuum layer region. This value , you then can refer to<br>so-called vacuum level.<br><br><br><div class="gmail_quote">
On Fri, Nov 14, 2008 at 10:36 AM, oulihui666 <span dir="ltr"><<a href="mailto:oulihui666@126.com">oulihui666@126.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div>Dear pwscf users,</div>
<div>I want to calculate work function, I have got the fermi level, so I must get the vacuum level.</div>
<div> <span style="font-size: 12pt; color: red;" lang="EN-US"><b>work = (vacuum level) - (fermi level)</b></span></div>
<div><span style="font-size: 12pt; color: red;" lang="EN-US">
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000">My input file displayed as follows:</font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000">(1)scf calculation:</font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US">&control<br> calculation='scf'<br>
restart_mode='from_scratch',<br> prefix='Al',<br> pseudo_dir = './',<br> outdir='./'<br> /<br> &system<br> ibrav= 0, nat=11, ntyp= 1,<br> ecutwfc =16, <br> occupations='smearing', smearing='methfessel-paxton', degauss=0.01<br>
/<br> &electrons<br> conv_thr = 1.0d-8<br> mixing_beta = 0.7<br> /<br>CELL_PARAMETERS cubic<br>5.41176 0 0<br>0 5.41176 0<br>0 0 60.9909 <br>ATOMIC_SPECIES<br>Al 13.867 Al.vbc.UPF <br>
ATOMIC_POSITIONS {angstrom}<br>Al 0 0 0<br>Al 1.43189 1.43189 2.025<br>Al 0 0 4.05<br>Al 1.43189 1.43189 6.075<br>Al 0 0 8.1<br>Al 1.43189 1.43189 10.125<br>Al 0 0 12.15<br>
Al 1.43189 1.43189 14.175<br>Al 0 0 16.2<br>Al 1.43189 143189 18.225<br>Al 0 0 20.25<br>K_POINTS {automatic}<br> 8 8 1 0 0 0<br></span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US">(2)Electrostatic potential calculation:</span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US"> &inputpp<br>
prefix = 'Al'<br> outdir = './'<br> filplot = 'Al.pot'<br> plot_num= 11<br> /<br></span></span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US">(3)<span style="font-size: 12pt;" lang="EN-US">macroscopic averages calculation: average.x.</span></span></span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 12pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US">1<br>
Al.pot<br>1.D0<br>5000<br>3<br>2.95<br></span></span></span></span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><font color="#000000"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US"><span style="font-size: 12pt;" lang="EN-US"><span style="font-size: 10.5pt;" lang="EN-US">Finally, I get a output file, <span style="font-size: 12pt;" lang="EN-US">column 1: coordinate u, <b><span style="color: red;">defined over a mesh of npt=5000 point</span></b>s along the direction idir=3, <span style="font-size: 12pt;" lang="EN-US">column 2: <b><span style="color: red;">averaged quantity</span></b> V, </span></span></span></span></span></span></font></span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">column 3: <b><span style="color: red;">macroscopically averaged quantity V</span></b>, I should how to get the vacuum level? any suggestion will be appreciated.</span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"></span> </p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">Thank you</span></p>
<p style="margin: 0cm 0cm 0pt; line-height: 150%;"><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">Lihui Ou</span></p></span></div>
<div><br>--<br>
<div>
<div><font face="Arial" size="3">======================================</font></div>
<div><font face="Arial" size="3">Lihui Ou</font></div>
<div><font face="Arial" size="3">PH.D Candidate in Electrochemistry </font></div>
<div><font face="Arial" size="3">College of Chemistry and Molecular Science </font></div>
<div><font face="Arial" size="3">Wuhan University,<i>430072</i>,Hubei Province,China </font></div>
<div><i><font face="Arial" size="3">E-mail:</font><a href="mailto:oulihui666@126.com" target="_blank"><font face="Arial" size="3">oulihui666@126.com</font></a></i></div>
<div><font face="Arial" size="3">======================================</font></div></div></div><br><br><hr>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Hai-Ping Lan <br>Department of Electronics ,<br>Peking University , Bejing, 100871<br><a href="mailto:lanhaiping@gmail.com">lanhaiping@gmail.com</a>, <a href="mailto:hplan@pku.edu.cn">hplan@pku.edu.cn</a><br>