First check the band-structure in bulk case. The smaller band-gap may be due to appearance of surface states in band-gap region.
----- Original Message ----- From: "LEUNG Clarence" <[email protected]> To: "pw forum" <[email protected]> Sent: Thursday, June 15, 2017 1:55:03 PM Subject: [Pw_forum] Problem on HSE bandgap caluculation Dear All, Now, I want to use HSE functional to calculate the band structure of monolayer arsenic, but the band gap is much smaller than previous report (2eV). I have try to change some parameters. But the results are not good. EXX= 0.25, ecutwfc=30, gap=1.15eV, EXX=0.35, ecutwfc=30, gap=0.89eV, EXX=0.15, ecutwfc=30, gap=1.40eV, EXX=0.10, ecutwfc=30, gap=1.56eV, EXX=0.05, ecutwfc=30, gap=1.63eV, EXX=0.25, ecutwfc=60, gap=1.15eV, The psudo-potential is norm-conserving: As 74.921600d0 As.pbe-mt_fhi.UPF And the input file as follow: &CONTROL calculation='scf' , verbosity='low', etot_conv_thr = 1.0D-5 , forc_conv_thr = 1.0D-4 , nstep = 200 , tstress = .false. , tprnfor = .false. , max_seconds = 320000 , wf_collect = .true. , / &SYSTEM ibrav=0, celldm(1)=27.2266448794d0, nat=32, ntyp=1, ecutwfc=30, input_dft='hse', occupations='smearing', smearing = 'gaussian' , degauss = 0.02 , nosym = .true. , vdw_corr = 'DFT-D' , nqx1 = 1, nqx2 = 1 , nqx3 = 1 , exx_fraction = 0.05, / &ELECTRONS conv_thr=1d-06, mixing_beta=0.3d0, electron_maxstep = 1000 , / &IONS ion_dynamics = 'bfgs', bfgs_ndim = 3 , / ATOMIC_SPECIES As 74.921600d0 As.pbe-mt_fhi.UPF ATOMIC_POSITIONS {crystal} As 0.083333304 0.041666531 0.465177578 As 0.166666686 0.208333294 0.534822422 As 0.083333418 0.291666706 0.465177578 As 0.166666800 0.458333469 0.534822384 As 0.333333200 0.041666531 0.465177578 As 0.416666582 0.208333294 0.534822422 As 0.333333366 0.291666706 0.465177578 As 0.416666748 0.458333469 0.534822384 As 0.083333304 0.541666531 0.465177578 As 0.166666686 0.708333294 0.534822422 As 0.083333418 0.791666706 0.465177578 As 0.166666800 0.958333469 0.534822384 As 0.333333200 0.541666531 0.465177578 As 0.416666582 0.708333294 0.534822422 As 0.333333366 0.791666706 0.465177578 As 0.416666748 0.958333469 0.534822384 As 0.583333304 0.041666531 0.465177578 As 0.666666686 0.208333294 0.534822422 As 0.583333418 0.291666706 0.465177578 As 0.666666800 0.458333469 0.534822384 As 0.833333200 0.041666531 0.465177578 As 0.916666582 0.208333294 0.534822422 As 0.833333366 0.291666706 0.465177578 As 0.916666748 0.458333469 0.534822384 As 0.583333304 0.541666531 0.465177578 As 0.666666686 0.708333294 0.534822422 As 0.583333418 0.791666706 0.465177578 As 0.666666800 0.958333469 0.534822384 As 0.833333200 0.541666531 0.465177578 As 0.916666582 0.708333294 0.534822422 As 0.833333366 0.791666706 0.465177578 As 0.916666748 0.958333469 0.534822384 K_POINTS 84 0.0000000 0.0000000 0.0000000 0.03125 0.0000000 0.1443377 0.0000000 0.06250 0.0000000 0.2886754 0.0000000 0.06250 0.0000000 0.4330131 0.0000000 0.06250 0.0000000 -0.5773508 0.0000000 0.03125 0.1250000 0.0721689 0.0000000 0.0625 0.1250000 0.2165066 0.0000000 0.0625 0.1250000 0.3608443 0.0000000 0.0625 0.1250000 0.5051820 0.0000000 0.0625 0.1250000 -0.5051820 0.0000000 0.0625 0.1250000 -0.3608443 0.0000000 0.0625 0.1250000 -0.2165066 0.0000000 0.0625 0.1250000 -0.0721689 0.0000000 0.0625 0.2500000 0.1443377 0.0000000 0.0625 0.2500000 0.2886754 0.0000000 0.0625 0.2500000 0.4330131 0.0000000 0.0625 0.2500000 0.5773508 0.0000000 0.0625 0.2500000 -0.4330131 0.0000000 0.0625 0.2500000 -0.2886754 0.0000000 0.0625 0.2500000 -0.1443377 0.0000000 0.0625 0.2500000 0.0000000 0.0000000 0.0625 0.3750000 0.2165066 0.0000000 0.0625 0.3750000 0.3608443 0.0000000 0.0625 0.3750000 0.5051820 0.0000000 0.0625 0.3750000 0.6495197 0.0000000 0.0625 0.3750000 -0.3608443 0.0000000 0.0625 0.3750000 -0.2165066 0.0000000 0.0625 0.3750000 -0.0721689 0.0000000 0.0625 0.3750000 0.0721689 0.0000000 0.0625 -0.500000 -0.2886754 0.0000000 0.03125 -0.500000 -0.1443377 0.0000000 0.0625 -0.500000 0.0000000 0.0000000 0.0625 -0.500000 0.1443377 0.0000000 0.0625 -0.500000 -0.8660262 0.0000000 0.03125 0.0000000000 0.0000000000 0.0000000000 0 0.0277777778 0.0000000000 0.0000000000 0 0.0555555556 0.0000000000 0.0000000000 0 0.0833333333 0.0000000000 0.0000000000 0 0.1111111111 0.0000000000 0.0000000000 0 0.1388888889 0.0000000000 0.0000000000 0 0.1666666667 0.0000000000 0.0000000000 0 0.1944444444 0.0000000000 0.0000000000 0 0.2222222222 0.0000000000 0.0000000000 0 0.2500000000 0.0000000000 0.0000000000 0 0.2777777778 0.0000000000 0.0000000000 0 0.3055555556 0.0000000000 0.0000000000 0 0.3333333333 0.0000000000 0.0000000000 0 0.3611111111 0.0000000000 0.0000000000 0 0.3888888889 0.0000000000 0.0000000000 0 0.4166666667 0.0000000000 0.0000000000 0 0.4444444444 0.0000000000 0.0000000000 0 0.4722222222 0.0000000000 0.0000000000 0 0.5000000000 0.0000000000 0.0000000000 0 0.4833330000 0.0333330000 0.0000000000 0 0.4666660000 0.0666660000 0.0000000000 0 0.4499990000 0.0999990000 0.0000000000 0 0.4333320000 0.1333320000 0.0000000000 0 0.4166650000 0.1666650000 0.0000000000 0 0.3999980000 0.1999980000 0.0000000000 0 0.3833310000 0.2333310000 0.0000000000 0 0.3666640000 0.2666640000 0.0000000000 0 0.3499970000 0.2999970000 0.0000000000 0 0.3333300000 0.3333300000 0.0000000000 0 0.3174571429 0.3174571429 0.0000000000 0 0.3015842857 0.3015842857 0.0000000000 0 0.2857114286 0.2857114286 0.0000000000 0 0.2698385714 0.2698385714 0.0000000000 0 0.2539657143 0.2539657143 0.0000000000 0 0.2380928571 0.2380928571 0.0000000000 0 0.2222200000 0.2222200000 0.0000000000 0 0.2063471429 0.2063471429 0.0000000000 0 0.1904742857 0.1904742857 0.0000000000 0 0.1746014286 0.1746014286 0.0000000000 0 0.1587285714 0.1587285714 0.0000000000 0 0.1428557143 0.1428557143 0.0000000000 0 0.1269828571 0.1269828571 0.0000000000 0 0.1111100000 0.1111100000 0.0000000000 0 0.0952371429 0.0952371429 0.0000000000 0 0.0793642857 0.0793642857 0.0000000000 0 0.0634914286 0.0634914286 0.0000000000 0 0.0476185714 0.0476185714 0.0000000000 0 0.0317457143 0.0317457143 0.0000000000 0 0.0158728571 0.0158728571 0.0000000000 0 0.0000000000 0.0000000000 0.0000000000 0 CELL_PARAMETERS {alat} 1.000000000000d0 0.000000000000d0 0.000000000000d0 -0.500000000000d0 0.866024603476d0 0.000000000000d0 0.000000000000d0 0.000000000000d0 1.388144689097d0 Best regards, Clarence CityU university of Hong Kong _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum _______________________________________________ Pw_forum mailing list [email 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