Dear Moon: there is no point in using any smearing in an insulator (but for plotting the DOS, possibly, but that would be for post-processing purposes only). In order to compute the DOS, you may want to try the tetrahedron method, which is implemented in QE, although I do not know exactly how … Otherwise, Gaussian (or any other smearing) would do, but only in the post-processing phase … HTH — SB
> On 7 Aug 2018, at 09:59, 문태환 <[email protected]> wrote: > > Dear Stefano, > > Your advice has helped a lot. > > If I can ask you one more question, can I calculate the fermi energy for > semiconductor material if I use DOS calculations using 'gaussian smearing' > instead of 'occupations = fixed'? > > Thank you again. > > > Moon Taehwan, chung-ang university > 보낸 사람: Stefano Baroni <[email protected] <mailto:[email protected]>> 대신 users > <[email protected] > <mailto:[email protected]>> > 보낸 날짜: 2018년 8월 7일 화요일 오후 4:42:30 > 받는 사람: Quantum Espresso users Forum > 제목: Re: [QE-users] How to obtain fermi energy through pDOS calculation of > quantum espresso? > > Hi ???, > > The energy zero in any infinite system is arbitrary. In the lack of a > surface, only energy differences matter. > The zero-temperature Fermi energy of an insulator is also arbitrary, though > usually assumed to lie at the middle of the gap. > > Hope this helps. > > Meanwhile, would you mind signing your posts with your name and affiliation? > > Thanks — Stefano B > >> On 7 Aug 2018, at 09:17, 문태환 <[email protected] <mailto:[email protected]>> >> wrote: >> >> Hello. I am a beginner to try DFT calculations using quantum espresso (GUI >> BURAI) for the first time. >> An attempt was made to calculate the SCF and pDOS using the CIF-file of the >> organic-inorganic hybrid material (eg MAPbI3). I wanted to get the fermi >> energy, but I could not find it in the output file of nscf, dos, pdos, scf, >> etc. because I was immature and calculated occupation as 'fixed'. >> The problem is that the energy of HOMO and LUMO is calculated as about 1.1 >> eV and 4.4 eV, and I want to know what is the criterion of 0 eV. >> >> If I use the gaussian smearing method, can I get the correct fermi energy? >> >> _______________________________________________ >> users mailing list >> [email protected] <mailto:[email protected]> >> https://lists.quantum-espresso.org/mailman/listinfo/users >> <https://lists.quantum-espresso.org/mailman/listinfo/users> > — > Stefano Baroni - SISSA, Trieste - http://stefano.baroni.me > <http://stefano.baroni.me/>, stefanobaroni (Skype) > > If the prediction that an airplane can stay up depends on the difference > between Riemann and Lebesgue integration, I don’t want to fly in it [Richard > W. Hammings] > > > > _______________________________________________ > users mailing list > [email protected] <mailto:[email protected]> > https://lists.quantum-espresso.org/mailman/listinfo/users > <https://lists.quantum-espresso.org/mailman/listinfo/users> — Stefano Baroni - Trieste — http://stefano.baroni.me <http://stefano.baroni.me/>
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