Dear Anup, Getting DFT to come close is going to be a challenge. You may find DOI: 10.1103/PhysRevMaterials.2.025001 useful. Some general comments:
1) In my experience +U is too harsh for 4f electrons. In your case 6eV is not that far below E_F and may well be in the same energy range as states for other elements (e.g. O). +U will force the occupied 4f low, the unoccupied high and this may not be appropriate. 2) The width of the valence region will be too small, because you are not including core hole effects. 3) The tabulated cross-sections for 4f (e.g. NIST) are horribly bad -- this is know experimentally but I do not know of any better calculations. 4) There is the problem of Spin-Orbit. One also has to worry about whether the correct parity of states is in the DFT, it is easy to get the wrong ones at least in the rare earth scandates. On Sun, Oct 20, 2019 at 1:49 PM Anup Shakya <npshaky...@gmail.com> wrote: > Dear Prof. Laurence, > > Thank you for your question. I have performed some magnetic measurements > on the sample for which I am doing DFT calculations, which suggests Sm to > be in Sm+3 state. At the same time I have performed ARPES measurements on > the single crystalline material, and from the ARPES measurements (which I > have performed) and the previous ARPES report on this sample it seems that > there are no Sm 4f states near the Fermi energy. This also suggests that Sm > exist in Sm+3 state. Now since Sm+3 state has an energy far below the Fermi > level around -6 eV and only Sm +2 states lie near the Fermi level (JPS > Conf. Proc. 3, 017038 (2014). So, I wanted to reproduce the band structure > by treating Sm 4f as core states and compare the DFT results and the ARPES > results. The other reason is that when I am doing GGA+U calculations using > various values of U, the DFT results are not matching with the observed > ARPES spectra. Looking forward to hearing from you. > > SIncerely, > Anup Pradhan Sakhya > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=uVSeK0Qr8Kl3rdemU6WJuYxDEzFZOL0opAcdg9goxe0&s=l6hhlfacgvmaZaMhbLnEaFzV72c9l0ZidWpCm4SWCME&e= > SEARCH the MAILING-LIST at: > https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwICAg&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=uVSeK0Qr8Kl3rdemU6WJuYxDEzFZOL0opAcdg9goxe0&s=DycLY_6qn0ps4Mt1fUJW1RYEVMItG9kUtP-RPtQ3Yz0&e= > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI Co-Editor, Acta Cryst A "Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Gyorgi
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