Hello all, I'm working on the beta-FeSe system. In the first step I have done a simple LDA calculation. Unfortunately, after adjusting ecutwfc and scf K_POINTS, I can’t get the relatively accurate result compared to VASP and wien2k (the result of VASP and wien2k agree well on the fermi surface). It’s likely that the pseudopotential has some problem or I miss some key steps. The input files are listed below.
fe_se.scf.in ``` &control calculation = 'scf' restart_mode='from_scratch', prefix='fe_se', pseudo_dir = '/home/tgzhou/softwares/qe_release_6.4/pseudo/', outdir='tempdir/' / &system ibrav= 6, celldm(1)= 7.124270293115536, celldm(3)= 10.431292329, nat= 4, ntyp= 2, ecutwfc = 120.0, localization_thr = 0.01, occupations='smearing', smearing='mp', degauss=0.02 / &electrons mixing_beta = 0.7, conv_thr = 1.0d-10 / ATOMIC_SPECIES Fe 55.845 Fe.pz-n-kjpaw_psl.1.0.0.UPF Se 78.96 Se.pz-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS crystal Fe 0.000000000 0.000000000 0.000000000 Fe 0.500000000 0.500000000 0.000000000 Se 0.000000000 0.500000000 0.768115942 Se 0.500000000 0.000000000 0.231884057 K_POINTS automatic 8 8 4 0 0 0 ``` fe_se.band.in ``` &control calculation='bands' pseudo_dir = '/home/tgzhou/softwares/qe_release_6.4/pseudo/', outdir='tempdir/', prefix='fe_se' / &system ibrav= 6, celldm(1)= 7.124270293115536, celldm(3)= 10.431292329, nat= 4, ntyp= 2, ecutwfc = 120.0, nbnd=20 / &electrons / ATOMIC_SPECIES Fe 55.845 Fe.pz-n-kjpaw_psl.1.0.0.UPF Se 78.96 Se.pz-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS crystal Fe 0.000000000 0.000000000 0.000000000 Fe 0.500000000 0.500000000 0.000000000 Se 0.000000000 0.500000000 0.768115942 Se 0.500000000 0.000000000 0.231884057 K_POINTS crystal_b 4 0.0 0.0 0.0 50 0.5 0.0 0.0 50 0.5 0.5 0.0 50 0.0 0.0 0.0 1 ``` The band structure is in the path \Gamma-X-M-\Gamma. And those two have some similarity but the qe FeSe band are much more narrow. qe FeSe band structure https://drive.google.com/file/d/1wG1Nm-f5v03-kfefJoPZ4gSD4rYaJSQa/view vasp FeSe band structure https://drive.google.com/file/d/1T0iNg7oecpey2dD6BB9iNrvjS6rm7Mnr/view Best, Tiangang Zhou School of Physics Peking University
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