Dear Quantum ESPRESSO developers and users, I am working on Ce₂O₃ and trying to reproduce the experimentally reported band gap (~2.4–2.7 eV) using LDA+U in combination with spin–orbit coupling (SOC) in Quantum ESPRESSO. However, despite using U = 6 eV and including SOC via fully relativistic pseudopotentials, the computed band gap is significantly underestimated (around 1.1 eV).
Here are the key points of my setup: - Code version: QE 7.X - Pseudopotential: Ce.pz-spdfn-rrkjus_psl.1.0.0.UPF (fully relativistic) - Functional: PZ-LDA - Hubbard_U applied: U = 6.0 eV on Ce 4f - Calculation type: SCF → bands - Structure: 5-atom primitive cell from literature (a = 3.87 Å, c/a = 1.522) - `nbnd = 41` - Gap is computed using `bands.x` and visual inspection Despite these, the gap remains ~1.1 eV. Literature reports higher values for similar setups. I also observe that relaxing the cell via `vc-relax` makes the lattice smaller, which further reduces the gap. Using experimental lattice constants does help, but not enough to reach the expected values. Could you please advise on: 1. Whether this pseudopotential is appropriate for SOC + LDA+U calculations on Ce? 2. Any suggestions on correcting the band gap underestimation? 3. Whether a better suited pseudopotential or approach (e.g., using GGA+U, HSE, etc.) is recommended? I am attaching the input file 4. I tried the same with Ce.pz-spdn-rrkjus_psl.1.0.0.UPF it gives band gap of 3.7 eV. shall i proceed with spdn? I would greatly appreciate your insights. -- *Thanks and with Regards, * *Aiswarya Chandran* *Research Scholar* *Laboratory for Advanced Materials and Applied Research* *Department of Chemistry* *NIT Calicut, Kerala, India, 673 601*
scf-ce2o3-new.in
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