How can I get the value of band gap.

[Lee]

I performed density of states calculations with pbe functionals for the Si unit cell.
I got the appropriate DOSCAR file from the calculation like this..
The fermi energy is "5.91004604 eV"
From the DOSCAR file, how can I measure the energy band gap under the value.
The density state is not zero at the fermi energy but the value is quite low. (E-02, E-04, E-08 ...)
I am very confused to analyze the data. Is there any criterion to measure the band gap?

Thank you very much.



DOSCAR file
...
...
...
4.695 0.4806E+01 0.3069E+02
4.771 0.3900E+01 0.3098E+02
4.846 0.2762E+01 0.3119E+02
4.922 0.2206E+01 0.3136E+02
4.998 0.1603E+01 0.3148E+02
5.074 0.1286E+01 0.3158E+02
5.150 0.6942E+00 0.3163E+02
5.226 0.7609E+00 0.3169E+02
5.302 0.1212E+01 0.3178E+02
5.378 0.8948E+00 0.3185E+02
5.454 0.7330E+00 0.3191E+02
5.529 0.7940E+00 0.3197E+02
5.605 0.3776E+00 0.3199E+02
5.681 0.6343E-01 0.3200E+02
5.757 0.3654E-02 0.3200E+02
5.833 0.7084E-04 0.3200E+02
5.909 0.4549E-06 0.3200E+02
5.985 0.1457E-08 0.3200E+02
6.061 0.2832E-06 0.3200E+02
6.137 0.5239E-04 0.3200E+02
6.212 0.3208E-02 0.3200E+02
6.288 0.6631E-01 0.3201E+02
6.364 0.4810E+00 0.3204E+02
6.440 0.1350E+01 0.3214E+02
6.516 0.1830E+01 0.3228E+02
6.592 0.1453E+01 0.3239E+02
6.668 0.5936E+00 0.3244E+02
6.744 0.3243E+00 0.3246E+02
6.820 0.1235E+01 0.3256E+02
6.895 0.2551E+01 0.3275E+02
6.971 0.2584E+01 0.3295E+02
7.047 0.2165E+01 0.3311E+02
7.123 0.3131E+01 0.3335E+02
7.199 0.4154E+01 0.3366E+02
...
...
...
...



<span class='smallblacktext'>[ Edited ]</span>

[kambiz]

Hi,
You may try this link:
http://theory.cm.utexas.edu/vtsttools/scripts/

Plot the DOS as a function of energy and the difference between the top of the valence band and the bottom of the conduction band is the Band gap.

Cheers

[tlchan]

I believe the small values of the DOS are related to the smearing. Maybe it is more straight forward to determine the gap by finding out the highest occupied state and the lowest unoccupied state in the OUTCAR.