<div>Hi Gui-Bin</div><div><br></div><div>To avoid intraband contribution it is not enough to use intrasmear=0, you also need to set occupations='fixed' in the PW calculations, at least for the nscf one. The following reads in the manual of epsilon.</div>
<div><br></div><div>\emph{intrasmear} is the broadening parameter for the intraband, i.e. metal Drude like term (again in eV), </div><div>the intraband contribution is calculated only if a Gaussian broadening or tetrahedron method it's been </div>
<div>applied in PW calculations.</div><div><br></div><div><br></div><div>On the other hand, it seems from the epsi plot, that the Wien calculation considers automatically a larger number of bands. You must set manually the parameter nbnd in the nscf calculations, and increase it until the dielectric function is converged. Check specially the convergence of epsr. nbnd determine the number of transitions (the peaks) observed in epsri. High energy transitions contribute in shifting the low energy values of epsr, as you can see looking at the Kramers-Kronig relations. </div>
<div><br></div><div>Best wishes</div><div>Eduardo</div><div><br></div><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">"<br>
<br>Today's Topics:<br>
<br>
1. Why dielectric function of only interband contribution has<br>
the features of intraband? (gbliu)<br>
<br><br>---------- Mensaje reenviado ----------<br>From: gbliu <<a href="mailto:goodluck_1982@163.com">goodluck_1982@163.com</a>><br>To: PWSCF Forum <<a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a>><br>
Date: Wed, 13 Jul 2011 01:04:28 +0800<br>Subject: [Pw_forum] Why dielectric function of only interband contribution has the features of intraband?<br><u></u>
<div text="#000000" bgcolor="#ffffff">
Dear PW users,<br>
<br>
I calculated the dielectric function of (3,3) Carbon nanotube
(CNT). However, the results for only interband contribution has the
features of intraband contribution! Attached figures show the
results of parallel polarization compared with wien2k (a FP-LAPW
software). Using "intrasmear = 0", the direct result of epsi.dat
should gives out only interband contributions, while epsr.dat is
added by "omega_p^2/omega^2" to get the interband contributions
only. And omega_p is obtained as <b>3.5679eV</b> by fitting the
difference of data with intrasmear=0 and intrasmear=0.1 using Drude
model "\epsilon_{intra}=1- omega_p^2/(omega^2+i*omega*intrasmear)".
How to understand this?<br>
<br>
Another problem is, fitted omega_p = 3.5679eV. This is far from
the result given by wien2k, 24.5eV! Which one is more reasonable?
And why?<br>
<br>
Can anyone help me? Thanks in advance!<br>
<br>
Best wishes,<br>
<br>
Liu Gui-Bin<br>
Dept. of Physics, The University of Hong Kong<br>
<br>
---------------input file for epsilon.x----------<br>
&inputpp<br>
outdir='./work'<br>
prefix='cnt33'<br>
calculation='eps'<br>
/<br>
&energy_grid<br>
smeartype='gauss'<br>
intersmear=0.1d0<br>
intrasmear=0d0<br>
wmax=30d0<br>
wmin=0d0<br>
nw=2000<br>
shift=0d0<br>
/<br>
----------------------------------------------------------<br>
</div>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div><br></div>
<div><br></div>Eduardo Menendez Proupin<div>Departamento de Química Fisica Aplicada<br>Facultad de Ciencias<br>Universidad Autónoma de Madrid</div><div>Phone: +34 91 497 6706</div><div><br></div><div>On leave from: Departamento de Fisica, Facultad de Ciencias, Universidad de Chile URL: <a href="http://fisica.ciencias.uchile.cl/~emenendez" target="_blank">http://fisica.ciencias.uchile.cl/~emenendez</a><div>
<br></div><div><span style="font-family:sans-serif;font-size:13px;line-height:19px">"<i>Padece, espera y trabaja para gentes que nunca conocerá y que a su vez padecerán, esperarán y trabajarán para otros, que tampoco serán felices, pues el hombre ansía siempre una felicidad situada más allá de la porción que le es otorgada. Pero la grandeza del hombre está precisamente en querer mejorar lo que es. En imponerse Tareas. En el Reino de los Cielos no hay grandeza que conquistar, puesto que allá todo es jerarquía establecida, incógnita despejada, existir sin término, imposibilidad de sacrificio, reposo y deleite. Por ello, agobiado de penas y de Tareas, hermoso dentro de su miseria, capaz de amar en medio de las plagas, el hombre puede hallar su grandeza, su máxima medida en el Reino de este Mundo</i>".</span></div>
<div><span style="font-family:sans-serif;font-size:13px;line-height:19px">Alejo Carpentier, El reino de este mundo, (1949).</span></div><div><font face="sans-serif"><span style="line-height:19px"><br></span></font></div><div>
<font face="sans-serif"><span style="line-height:19px">Translate from spanish here <a href="http://translate.google.com/?hl=&ie=UTF-8&text=&sl=es&tl=en" target="_blank">http://translate.google.com/?hl=&ie=UTF-8&text=&sl=es&tl=en</a></span></font></div>
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