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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hi!,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I am doing the work function calculation on carbon
nanotubes. If I am not mistaken, the scf calculation should give me Fermi
energy or midgap between HOMO and LUMO. Then, one can use pp.x plot_num 1 to
generate the total potential profile. The work function is decided by the
difference between the Fermi energy and the potential energy at the vaccum of
the supercell. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>However, I am running into a problem that the Fermi energy
from scf (1.65 ev) is higher than any potential inside the entire supercell
(ranging from -10.4 to 0.4 eV). When I looked at both the charge and
potential profiles, they seemed to suggest the Fermi energy should be somewhere
around -4 eV, which is not even close to the value scf reported. I am very
confused now. What is the Fermi energy I can use? Any thoughts on this? <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Tuo-Hung<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>_______________________________________</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Tuo-Hung Hou</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:PlaceName w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Cornell</span></font></st1:PlaceName><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <st1:PlaceType
w:st="on">University</st1:PlaceType></span></font></st1:place><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>School of Electrical and Computer Engineering</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>325 Phillips Hall</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:City w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Ithaca</span></font></st1:City><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>, <st1:State
w:st="on">NY</st1:State> <st1:PostalCode w:st="on">14853</st1:PostalCode></span></font></st1:place><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>phone: 607.255.4181</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>email : <a href="mailto:th273@cornell.edu">th273@cornell.edu</a></span></font><o:p></o:p></p>
<p class=MsoNormal style='line-height:15.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'> </span></font><font
size=1 face="Palatino Linotype"><span style='font-size:7.0pt;font-family:"Palatino Linotype"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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