Dear PWSCF users and developers: I have been trying to use PWSCF's implementation of LDA+U to calculate the electronic structure of CaCuO2 lately. In VASP, once I turn on U, it gives AFM ground state and reasonable gap separation at E_F. However, the procedure seems to be much harder for PWSCF. While it gets AFM gs correctly, I can never get a band gap. I searched the forum, and I realized that the initial occupation number might be important, but the several combinations I tried seem to give me the same result. So, is there any hint or suggestions, especially how to choose initial occupation numbers? Thanks in advance.
Best, Chao Cao And, here's my input file: &control calculation = 'scf' restart_mode = 'from_scratch' prefix = 'CaCuO2' disk_io = 'low' outdir = './' / &system ibrav = 0, celldm(1) = 1.88972688, ntyp = 4, nat = 16 nbnd=80, ecutwfc = 32, ecutrho = 400 nspin = 2, starting_magnetization(2)=0.5, starting_magnetization(3)=-0.5 lda_plus_u = .true., Hubbard_U(2) = 6.5, Hubbard_U(3) = 6.5 occupations = 'smearing', smearing = 'mp', degauss = 0.007 / &electrons mixing_beta = 0.2 conv_thr = 1.0d-9 / ATOMIC_SPECIES Ca 1.0 Ca.pbe-nsp-van.UPF Cuu 1.0 Cu.pbe-n-van.UPF Cud 1.0 Cu.pbe-n-van.UPF O 1.0 O.pbe-van.UPF ATOMIC_POSITIONS crystal Ca 0.25 0.75 0.25 Ca 0.75 0.25 0.25 Ca 0.25 0.75 0.75 Ca 0.75 0.25 0.75 Cuu 0.25 0.25 0.00 Cuu 0.75 0.75 0.50 Cud 0.75 0.75 0.00 Cud 0.25 0.25 0.50 O 0.00 0.00 0.00 O 0.50 0.00 0.00 O 0.00 0.50 0.00 O 0.50 0.50 0.00 O 0.00 0.00 0.50 O 0.50 0.00 0.50 O 0.00 0.50 0.50 O 0.50 0.50 0.50 K_POINTS automatic 8,8,4,1,1,1 CELL_PARAMETERS cubic 3.878393250 3.878393249 0.000000000 -3.878393249 3.878393250 0.000000000 0.000000000 0.000000000 6.409031058 -- Chao Cao Quantum Theory Project and Department of Physics University of Florida, Gainesville, FL 32611 U.S.A.
