Hi Gui-Bin 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.
\emph{intrasmear} is the broadening parameter for the intraband, i.e. metal Drude like term (again in eV), the intraband contribution is calculated only if a Gaussian broadening or tetrahedron method it's been applied in PW calculations. 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. Best wishes Eduardo > > " >> >> Today's Topics: >> >> 1. Why dielectric function of only interband contribution has >> the features of intraband? (gbliu) >> >> >> ---------- Mensaje reenviado ---------- >> From: gbliu <goodluck_1982 at 163.com> >> To: PWSCF Forum <pw_forum at pwscf.org> >> Date: Wed, 13 Jul 2011 01:04:28 +0800 >> Subject: [Pw_forum] Why dielectric function of only interband contribution >> has the features of intraband? >> ** >> Dear PW users, >> >> 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 *3.5679eV* 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? >> >> 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? >> >> Can anyone help me? Thanks in advance! >> >> Best wishes, >> >> Liu Gui-Bin >> Dept. of Physics, The University of Hong Kong >> >> ---------------input file for epsilon.x---------- >> &inputpp >> outdir='./work' >> prefix='cnt33' >> calculation='eps' >> / >> &energy_grid >> smeartype='gauss' >> intersmear=0.1d0 >> intrasmear=0d0 >> wmax=30d0 >> wmin=0d0 >> nw=2000 >> shift=0d0 >> / >> ---------------------------------------------------------- >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- > > > Eduardo Menendez Proupin > Departamento de Qu?mica Fisica Aplicada > Facultad de Ciencias > Universidad Aut?noma de Madrid > Phone: +34 91 497 6706 > > On leave from: Departamento de Fisica, Facultad de Ciencias, Universidad de > Chile URL: http://fisica.ciencias.uchile.cl/~emenendez > > "*Padece, espera y trabaja para gentes que nunca conocer? y que a su vez > padecer?n, esperar?n y trabajar?n para otros, que tampoco ser?n felices, > pues el hombre ans?a siempre una felicidad situada m?s all? de la porci?n > que le es otorgada. Pero la grandeza del hombre est? precisamente en querer > mejorar lo que es. En imponerse Tareas. En el Reino de los Cielos no hay > grandeza que conquistar, puesto que all? todo es jerarqu?a establecida, > inc?gnita despejada, existir sin t?rmino, 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 m?xima medida en el Reino de este Mundo*". > Alejo Carpentier, El reino de este mundo, (1949). > > Translate from spanish here > http://translate.google.com/?hl=&ie=UTF-8&text=&sl=es&tl=en > > -- Eduardo Menendez Proupin Departamento de Qu?mica Fisica Aplicada Facultad de Ciencias Universidad Aut?noma de Madrid Phone: +34 91 497 6706 On leave from: Departamento de Fisica, Facultad de Ciencias, Universidad de Chile URL: http://fisica.ciencias.uchile.cl/~emenendez "*Padece, espera y trabaja para gentes que nunca conocer? y que a su vez padecer?n, esperar?n y trabajar?n para otros, que tampoco ser?n felices, pues el hombre ans?a siempre una felicidad situada m?s all? de la porci?n que le es otorgada. Pero la grandeza del hombre est? precisamente en querer mejorar lo que es. En imponerse Tareas. En el Reino de los Cielos no hay grandeza que conquistar, puesto que all? todo es jerarqu?a establecida, inc?gnita despejada, existir sin t?rmino, 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 m?xima medida en el Reino de este Mundo*". Alejo Carpentier, El reino de este mundo, (1949). Translate from spanish here http://translate.google.com/?hl=&ie=UTF-8&text=&sl=es&tl=en -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110715/b51c5720/attachment-0001.htm