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<p>Thank for you reply.</p>
<p><br>
</p>
<p>From the experimental results, bulk are semi-metal.</p>
<p><br>
</p>
<p>Other DFT method with HSE show the band gap of monolayer is 2.0eV.</p>
<p><br>
</p>
<p>When I use PBE functional, the gap is 1.6eV which is agreed well with other calculation with PBE method.</p>
<p><br>
</p>
<p>Best regards,</p>
<p>Clarence</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>发件人:</b> pw_forum-bounces@pwscf.org <pw_forum-bounces@pwscf.org> 代表 sanjaynayak@jncasr.ac.in <sanjaynayak@jncasr.ac.in><br>
<b>发送时间:</b> 2017年6月15日 16:52:34<br>
<b>收件人:</b> PWSCF Forum<br>
<b>主题:</b> Re: [Pw_forum] Problem on HSE bandgap caluculation</font>
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<font size="2"><span style="font-size:10pt;">
<div class="PlainText">First check the band-structure in bulk case. The smaller band-gap may be
<br>
due to appearance of surface states in band-gap region.<br>
<br>
----- Original Message -----<br>
From: "LEUNG Clarence" <liangxy123@hotmail.com><br>
To: "pw forum" <pw_forum@pwscf.org><br>
Sent: Thursday, June 15, 2017 1:55:03 PM<br>
Subject: [Pw_forum] Problem on HSE bandgap caluculation<br>
<br>
<br>
<br>
<br>
<br>
Dear All, <br>
<br>
<br>
<br>
<br>
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).
<br>
<br>
<br>
<br>
<br>
I have try to change some parameters. But the results are not good. <br>
<br>
<br>
<br>
<br>
EXX= 0.25, ecutwfc=30, gap=1.15eV, <br>
<br>
EXX=0.35, ecutwfc=30, gap=0.89eV, <br>
<br>
EXX=0.15, ecutwfc=30, gap=1.40eV, <br>
<br>
<br>
EXX=0.10, ecutwfc=30, gap=1.56eV, <br>
<br>
<br>
EXX=0.05, ecutwfc=30, gap=1.63eV, <br>
<br>
<br>
EXX=0.25, ecutwfc=60, gap=1.15eV, <br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
The psudo-potential is norm-conserving: <br>
<br>
As 74.921600d0 As.pbe-mt_fhi.UPF <br>
<br>
<br>
<br>
<br>
<br>
And the input file as follow: <br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
&CONTROL <br>
calculation='scf' , <br>
<br>
verbosity='low', <br>
etot_conv_thr = 1.0D-5 , <br>
forc_conv_thr = 1.0D-4 , <br>
nstep = 200 , <br>
tstress = .false. , <br>
tprnfor = .false. , <br>
max_seconds = 320000 , <br>
wf_collect = .true. , <br>
/ <br>
<br>
<br>
&SYSTEM <br>
ibrav=0, <br>
celldm(1)=27.2266448794d0, <br>
nat=32, <br>
ntyp=1, <br>
ecutwfc=30, <br>
input_dft='hse', <br>
occupations='smearing', <br>
smearing = 'gaussian' , <br>
degauss = 0.02 , <br>
nosym = .true. , <br>
vdw_corr = 'DFT-D' , <br>
nqx1 = 1, <br>
nqx2 = 1 , <br>
nqx3 = 1 , <br>
exx_fraction = 0.05, <br>
/ <br>
<br>
<br>
&ELECTRONS <br>
conv_thr=1d-06, <br>
mixing_beta=0.3d0, <br>
electron_maxstep = 1000 , <br>
/ <br>
&IONS <br>
ion_dynamics = 'bfgs', <br>
bfgs_ndim = 3 , <br>
/ <br>
ATOMIC_SPECIES <br>
As 74.921600d0 As.pbe-mt_fhi.UPF <br>
<br>
<br>
ATOMIC_POSITIONS {crystal} <br>
As 0.083333304 0.041666531 0.465177578 <br>
As 0.166666686 0.208333294 0.534822422 <br>
As 0.083333418 0.291666706 0.465177578 <br>
As 0.166666800 0.458333469 0.534822384 <br>
As 0.333333200 0.041666531 0.465177578 <br>
As 0.416666582 0.208333294 0.534822422 <br>
As 0.333333366 0.291666706 0.465177578 <br>
As 0.416666748 0.458333469 0.534822384 <br>
As 0.083333304 0.541666531 0.465177578 <br>
As 0.166666686 0.708333294 0.534822422 <br>
As 0.083333418 0.791666706 0.465177578 <br>
As 0.166666800 0.958333469 0.534822384 <br>
As 0.333333200 0.541666531 0.465177578 <br>
As 0.416666582 0.708333294 0.534822422 <br>
As 0.333333366 0.791666706 0.465177578 <br>
As 0.416666748 0.958333469 0.534822384 <br>
As 0.583333304 0.041666531 0.465177578 <br>
As 0.666666686 0.208333294 0.534822422 <br>
As 0.583333418 0.291666706 0.465177578 <br>
As 0.666666800 0.458333469 0.534822384 <br>
As 0.833333200 0.041666531 0.465177578 <br>
As 0.916666582 0.208333294 0.534822422 <br>
As 0.833333366 0.291666706 0.465177578 <br>
As 0.916666748 0.458333469 0.534822384 <br>
As 0.583333304 0.541666531 0.465177578 <br>
As 0.666666686 0.708333294 0.534822422 <br>
As 0.583333418 0.791666706 0.465177578 <br>
As 0.666666800 0.958333469 0.534822384 <br>
As 0.833333200 0.541666531 0.465177578 <br>
As 0.916666582 0.708333294 0.534822422 <br>
As 0.833333366 0.791666706 0.465177578 <br>
As 0.916666748 0.958333469 0.534822384 <br>
<br>
<br>
K_POINTS <br>
84 <br>
0.0000000 0.0000000 0.0000000 0.03125 <br>
0.0000000 0.1443377 0.0000000 0.06250 <br>
0.0000000 0.2886754 0.0000000 0.06250 <br>
0.0000000 0.4330131 0.0000000 0.06250 <br>
0.0000000 -0.5773508 0.0000000 0.03125 <br>
0.1250000 0.0721689 0.0000000 0.0625 <br>
0.1250000 0.2165066 0.0000000 0.0625 <br>
0.1250000 0.3608443 0.0000000 0.0625 <br>
0.1250000 0.5051820 0.0000000 0.0625 <br>
0.1250000 -0.5051820 0.0000000 0.0625 <br>
0.1250000 -0.3608443 0.0000000 0.0625 <br>
0.1250000 -0.2165066 0.0000000 0.0625 <br>
0.1250000 -0.0721689 0.0000000 0.0625 <br>
0.2500000 0.1443377 0.0000000 0.0625 <br>
0.2500000 0.2886754 0.0000000 0.0625 <br>
0.2500000 0.4330131 0.0000000 0.0625 <br>
0.2500000 0.5773508 0.0000000 0.0625 <br>
0.2500000 -0.4330131 0.0000000 0.0625 <br>
0.2500000 -0.2886754 0.0000000 0.0625 <br>
0.2500000 -0.1443377 0.0000000 0.0625 <br>
0.2500000 0.0000000 0.0000000 0.0625 <br>
0.3750000 0.2165066 0.0000000 0.0625 <br>
0.3750000 0.3608443 0.0000000 0.0625 <br>
0.3750000 0.5051820 0.0000000 0.0625 <br>
0.3750000 0.6495197 0.0000000 0.0625 <br>
0.3750000 -0.3608443 0.0000000 0.0625 <br>
0.3750000 -0.2165066 0.0000000 0.0625 <br>
0.3750000 -0.0721689 0.0000000 0.0625 <br>
0.3750000 0.0721689 0.0000000 0.0625 <br>
-0.500000 -0.2886754 0.0000000 0.03125 <br>
-0.500000 -0.1443377 0.0000000 0.0625 <br>
-0.500000 0.0000000 0.0000000 0.0625 <br>
-0.500000 0.1443377 0.0000000 0.0625 <br>
-0.500000 -0.8660262 0.0000000 0.03125 <br>
0.0000000000 0.0000000000 0.0000000000 0 <br>
0.0277777778 0.0000000000 0.0000000000 0 <br>
0.0555555556 0.0000000000 0.0000000000 0 <br>
0.0833333333 0.0000000000 0.0000000000 0 <br>
0.1111111111 0.0000000000 0.0000000000 0 <br>
0.1388888889 0.0000000000 0.0000000000 0 <br>
0.1666666667 0.0000000000 0.0000000000 0 <br>
0.1944444444 0.0000000000 0.0000000000 0 <br>
0.2222222222 0.0000000000 0.0000000000 0 <br>
0.2500000000 0.0000000000 0.0000000000 0 <br>
0.2777777778 0.0000000000 0.0000000000 0 <br>
0.3055555556 0.0000000000 0.0000000000 0 <br>
0.3333333333 0.0000000000 0.0000000000 0 <br>
0.3611111111 0.0000000000 0.0000000000 0 <br>
0.3888888889 0.0000000000 0.0000000000 0 <br>
0.4166666667 0.0000000000 0.0000000000 0 <br>
0.4444444444 0.0000000000 0.0000000000 0 <br>
0.4722222222 0.0000000000 0.0000000000 0 <br>
0.5000000000 0.0000000000 0.0000000000 0 <br>
0.4833330000 0.0333330000 0.0000000000 0 <br>
0.4666660000 0.0666660000 0.0000000000 0 <br>
0.4499990000 0.0999990000 0.0000000000 0 <br>
0.4333320000 0.1333320000 0.0000000000 0 <br>
0.4166650000 0.1666650000 0.0000000000 0 <br>
0.3999980000 0.1999980000 0.0000000000 0 <br>
0.3833310000 0.2333310000 0.0000000000 0 <br>
0.3666640000 0.2666640000 0.0000000000 0 <br>
0.3499970000 0.2999970000 0.0000000000 0 <br>
0.3333300000 0.3333300000 0.0000000000 0 <br>
0.3174571429 0.3174571429 0.0000000000 0 <br>
0.3015842857 0.3015842857 0.0000000000 0 <br>
0.2857114286 0.2857114286 0.0000000000 0 <br>
0.2698385714 0.2698385714 0.0000000000 0 <br>
0.2539657143 0.2539657143 0.0000000000 0 <br>
0.2380928571 0.2380928571 0.0000000000 0 <br>
0.2222200000 0.2222200000 0.0000000000 0 <br>
0.2063471429 0.2063471429 0.0000000000 0 <br>
0.1904742857 0.1904742857 0.0000000000 0 <br>
0.1746014286 0.1746014286 0.0000000000 0 <br>
0.1587285714 0.1587285714 0.0000000000 0 <br>
0.1428557143 0.1428557143 0.0000000000 0 <br>
0.1269828571 0.1269828571 0.0000000000 0 <br>
0.1111100000 0.1111100000 0.0000000000 0 <br>
0.0952371429 0.0952371429 0.0000000000 0 <br>
0.0793642857 0.0793642857 0.0000000000 0 <br>
0.0634914286 0.0634914286 0.0000000000 0 <br>
0.0476185714 0.0476185714 0.0000000000 0 <br>
0.0317457143 0.0317457143 0.0000000000 0 <br>
0.0158728571 0.0158728571 0.0000000000 0 <br>
0.0000000000 0.0000000000 0.0000000000 0 <br>
<br>
<br>
<br>
<br>
<br>
<br>
CELL_PARAMETERS {alat} <br>
1.000000000000d0 0.000000000000d0 0.000000000000d0 <br>
-0.500000000000d0 0.866024603476d0 0.000000000000d0 <br>
0.000000000000d0 0.000000000000d0 1.388144689097d0 <br>
<br>
<br>
Best regards, <br>
Clarence <br>
CityU university of Hong Kong <br>
<br>
<br>
<br>
<br>
<br>
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