[Pw_forum] 答复: [Pw_forum] The band gap problem

[#TAO JUNGUANG#]

Yes, it is very strange, even it agree very well with the experiment value (3.2eV). so I am wonder if there are something wrong. And I have double checked my input file, nothing I have got. So I put important part of my input/output file in the following, hope there is someone who can help me.
   


Input file:
  &CONTROL
  calculation='nscf',
  restart_mode='from_scratch',
   pseudo_dir='/home/tao/pseudo/',
  prefix='TiO2',
   tstress=.true.
  tprnfor=.true.
/
&SYSTEM
 ibrav=6, a=4.594,c=2.958, nat=6,ntyp=2,
 ecutwfc=50,ecutrho=300,nbnd=32
/
&ELECTRONS
  conv_thr=1.0d-8,
  mixing_beta=0.7,
  mixing_mode='plain',
/

ATOMIC_SPECIES
 Ti  47.867   Ti.vdb.UPF
 O   15.9994  O.vdb.UPF

ATOMIC_POSITIONS crystal
Ti 0.00 0.00 0.00
Ti 0.5  0.5  0.5
O  0.3053 0.3053 0.00
O  0.6947 0.6947 0.00
O  0.1947 0.8053 0.50
O  0.8053 0.1947 0.50
K_POINTS 
36
 .........
Output file 

 k = 0.0000 0.0000 0.0000     band energies (ev):

   -48.0513 -48.0328 -24.6394 -24.6394 -24.5918 -24.5555 -24.4560 -24.4560
   -10.8949  -9.9359  -9.1136  -9.1136   1.4513   1.7754   2.9432   3.3134
     3.3134   4.5065   4.5065   4.9294   5.9502   6.2828   6.2828   6.9172
    10.1728  10.2878  10.7490  10.7491  10.8082  12.5115  12.6253  14.3036

 10.1728-6.9172=3.2556