[Pw_forum] why is the tetrahedron interpolated DOS step-like?
Dear all, I would like to know if the step-like aspect of a DOS calculated with the tetrahedron interpolation is what is expected to be. Please, take a look at the figures attached. I would expect something soft or at least a polygonal line with slope. I have looked at flib/dost.f90 and checked that the interpolation formulae are the same of the Bloechl's article OK. I am sorry to ask such a basic question, but I am puzzled since a long time, and tired of soften the stepped line with an additional program. Thanks in advance -- Eduardo Menendez Proupin Departamento de Qu?mica Fisica Aplicada Facultad de Ciencias Universidad Aut?noma de Madrid 28049 Madrid, Spain 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/20111209/946491a6/attachment-0001.htm -- next part -- A non-text attachment was scrubbed... Name: dos-tetra.jpeg Type: image/jpeg Size: 42328 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20111209/946491a6/attachment-0002.jpeg -- next part -- A non-text attachment was scrubbed... Name: dos-tetra2.jpeg Type: image/jpeg Size: 33191 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20111209/946491a6/attachment-0003.jpeg
[Pw_forum] Al pseudopotential and elastic properties
e 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/20111209/9ec46c3d/attachment.htm
[Pw_forum] why is the tetrahedron interpolated DOS step-like?
On Dec 9, 2011, at 13:33 , Eduardo Ariel Menendez Proupin wrote: > I would like to know if the step-like aspect of a DOS calculated with > the tetrahedron interpolation is what is expected to be. Please, take > a look at the figures attached. your system is quasi-1d, or at least, the k-point grid is, am I correct? In that case, I am afraid that what you get is what you should get. I am actually surprised that it works at all! Notice that the "steps" in tetrahedron DOS exactly correspond to the "peaks" in gaussian DOS. Paolo (guilty of the tetrahedron implementation) --- Paolo Giannozzi, Dept of Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
[Pw_forum] why is the tetrahedron interpolated DOS step-like?
The system is 1-D, with a 18 angstrom wide supercell. I suspected that 1-D tetrahedra are not very tetrahedral, and used a 2x2x28 k-points grid. It gives the same result than with a 1x1x28 grid, and the DOS numbers differ in the third decimal digit. Eduardo On Dec 9, 2011, at 13:33 , Eduardo Ariel Menendez Proupin wrote: >* I would like to know if the step-like aspect of a DOS calculated with*>* the >tetrahedron interpolation is what is expected to be. Please, take*>* a look at >the figures attached.* your system is quasi-1d, or at least, the k-point grid is, am I correct? In that case, I am afraid that what you get is what you should get. I am actually surprised that it works at all! Notice that the "steps" in tetrahedron DOS exactly correspond to the "peaks" in gaussian DOS. Paolo (guilty of the tetrahedron implementation) -- Eduardo Menendez Proupin Departamento de Qu?mica Fisica Aplicada Facultad de Ciencias Universidad Aut?noma de Madrid 28049 Madrid, Spain 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/20111209/0d4f15e3/attachment.htm
[Pw_forum] XSpectrum
Because in that case the code would assume that the excited electron occupies the lowest available conduction state, whereas in the experiment that you are correctly describing the core electron would be excited to some high-lying conduction band. On more physical grounds, the code simulates photoionization process, rather that than a photoexcitation one. When the final energy of the excited electron is high enough, however, the two processes are indistinguishable. SB On Dec 8, 2011, at 9:46 PM, Hanghui Chen wrote: > To QE developers, > In the examples of X-ray Spectrum calculations, I noticed that for > diamond, there are two different calculations. In one of them (the so-called > Z approximation), 8 normal carbon atoms are employed. In the other one (Z+1 > approximation), in addition to 7 normal carbon atoms, a special carbon atom > is employed with a fixed hole in its valence (basically, it is N atom. > Correct me if I am wrong.) What I am confused is that in the Z+1 > approximation, the input file specifies the number of electron to be 8*4=32. > Since the special carbon atom has valence 5 (instead of 4), the system is > charged. However, my understanding of x-ray absorption is that an incoming > photon excites an electron from 1s state into the conduction band. If that is > the case, then why not run a charge neutral calculation, i.e. nele = > 7*4+5=33, and the resulting system is metallic? > Thank you. > > Hanghui Chen > Department of Physics > Yale University > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype) La morale est une logique de l'action comme la logique est une morale de la pens?e - Jean Piaget -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20111209/a4432af8/attachment-0001.htm
[Pw_forum] why is the tetrahedron interpolated DOS step-like?
Eduardo: you may want to rehearse the theory of critical points, such as explained in many solid-state texts, my favorite one (at least in this field) still being Bassani and Pastori Parravicini's. SB On Dec 9, 2011, at 1:33 PM, Eduardo Ariel Menendez Proupin wrote: > Dear all, > > I would like to know if the step-like aspect of a DOS calculated with the > tetrahedron interpolation is what is expected to be. Please, take a look at > the figures attached. I would expect something soft or at least a polygonal > line with slope. > > I have looked at flib/dost.f90 and checked that the interpolation formulae > are the same of the Bloechl's article OK. > I am sorry to ask such a basic question, but I am puzzled since a long time, > and tired of soften the stepped line with an additional program. > Thanks in advance > -- > > > Eduardo Menendez Proupin > Departamento de Qu?mica Fisica Aplicada > Facultad de Ciencias > Universidad Aut?noma de Madrid > 28049 Madrid, Spain > 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 > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype) La morale est une logique de l'action comme la logique est une morale de la pens?e - Jean Piaget -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20111209/16c3817b/attachment.htm
[Pw_forum] why is the tetrahedron interpolated DOS step-like?
>Eduardo: you may want to rehearse the theory of critical points, such as >explained in many solid-state texts, my favorite one (at least in this field) >still being Bassani and Pastori Parravicini's. SB Stefano, Thank you. You are right if the system is 2D, but in this case it is quasi-1D. The 1-D Van Hove singularitu is appreciated in the large energy scale of the plot between -6 and -4 eV. Maybe the steps in the low energy scale reveal that a quasi-1D system with a finite k-point sampling is an effective bi-dimensionality with a smaller energy scale, with as many bands as k-points. I do not think that you are meaning that, as k-points sampling is not a matter of solid state textbooks. Thanks, and nice weekend Eduardo On Dec 9, 2011, at 1:33 PM, Eduardo Ariel Menendez Proupin wrote: >* Dear all,*>* *>* I would like to know if the step-like aspect of a DOS >calculated with the tetrahedron interpolation is what is expected to be. >Please, take a look at the figures attached. I would expect something soft or >at least a polygonal line with slope. *>* *>* I have looked at flib/dost.f90 >and checked that the interpolation formulae are the same of the Bloechl's >article OK.*>* I am sorry to ask such a basic question, but I am puzzled since >a long time, and tired of soften the stepped line with an additional program. >*>* Thanks in advance* -- -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20111209/0fbda415/attachment.htm
