Hello everyone,
I'm currently performing a VASP calculation to get the bandstructure and the density of space of LaNiO3 but I'm not convinced by my results. First of all the bandstructure is almost unreadable (cf. figures). I was wondering how can I get something more readable and how can I customize the energy range of the bandstructure ?
I join the INCAR file if it can help.
This band structure is representative of a zero band gap material which is not the case for your crystal, I guess. Some methods underestimate the band gap and usually you can't solve the problem by just modifying the input parameters. Maybe you should assess other methods (e.g. B3LYP hybrid functional) in order to adopt a precise method for this material.
Dear Benjamin,
If you're just bored from the many intersecting bands, you can use INCAR options to tell VASP to only output bands within a certain energy range.
Concerning the accuracy of results, I've answered several colleagues so far that the DFT , which is built-in by default in VASP-underestimates the energy gap of almost all insulators and semiconductors. The solution is to use either advanced hybrid functionals, or better use a many-body quantum perturbation method (e.g., DFpT or GWA).
Best wishes.
Dear Ehsan Moradpur-Tari, thank you for your answer. According to Article Electronic structure and optical properties of LaNiO 3: Firs...
there is no bandgap in this material. I was just wondering if there is a way to get a more readable bandgap. But I'm curious about the B3LYP hybrid functional method. I think it's the "GGA = B3" in the VASP INCAR file. What is your advice about the use of that instruction. Should I introduce it only in the fourth step (bandstructure calculation) or should I introduce it earlier ? (relaxation step or SCF calculation step)Dear Muhammad Hamza El-Saba , thank you too for your answer. You're right, I'm bored about all that intersecting band. I tried to use the EMIN and EMAX parameters in the INCAR file for the band structure calculation but it didn't change the final result. Should I introduce these parameters in a earlier step such as relaxation or SCF calculation ?
Another question is whether I should do a calculation with ISPIN = 2 or whether it is unnecessary? I ask this because in all the articles I have read, there is no difference between spin up and spin down in the electron structures
Benjamin Martin Yes. The tag you mentioned is used for B3LYP. I've seen articles that apparently used this method for ionic relaxation too, but it seems so demanding computationally.
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