# [Pw_forum] Fermi Energy and DOS

xshen xshen at ic.sunysb.edu
Wed Aug 9 07:06:15 CEST 2006

```Hi:

I am doing calculation of DOS of a supercell system. I did the scf
calculation first and then a nscf calculation for the DOS. The scf and
nscf calculations give me similar value of Fermi energy. however when I
checked  the total DOS state, I found that the  "Int dos" at the given
Fermi energy is not equal to the total number of electrons in my system.
Should I use the Fermi energy the program gives me, or pick the energy
where the "Int dos" is equal to my # of electrons?

The data is here .
scf calculation gives : Fermi energy is    -0.3788 ev
nscf calculation gives : Fermi energy is    -0.3892 ev

My system has 234 electrons, however at E= -0.4, the INT dos is 225.2.
If I want INT dos =234, the energy is between 2.500 and 2.600 ev.

Part of the Dos file:

#  E (eV)   dos(E)     Int dos(E)
-0.500  0.8034E-83  0.2252E+03
-0.400  0.2168E-78  0.2252E+03
-0.300  0.3285E-41  0.2252E+03
-0.200  0.9263E-16  0.2252E+03
-0.100  0.4941E-02  0.2252E+03
0.000  0.2989E+01  0.2255E+03
0.100  0.1309E+01  0.2256E+03
0.200  0.5846E+00  0.2257E+03
0.300  0.9425E+00  0.2258E+03
0.400  0.9223E+00  0.2259E+03
0.500  0.5458E+00  0.2259E+03
0.600  0.1596E+00  0.2259E+03
0.700  0.4433E-01  0.2259E+03
0.800  0.2465E+00  0.2260E+03
0.900  0.1201E+01  0.2261E+03
1.000  0.2066E+01  0.2263E+03
1.100  0.9347E+00  0.2264E+03
1.200  0.1511E+00  0.2264E+03
1.300  0.8143E+01  0.2272E+03
1.400  0.4891E+01  0.2277E+03
1.500  0.4694E+01  0.2282E+03
1.600  0.4475E+01  0.2286E+03
1.700  0.2586E+01  0.2289E+03
1.800  0.1381E+01  0.2290E+03
1.900  0.2355E+01  0.2293E+03
2.000  0.3072E+01  0.2296E+03
2.100  0.3584E+01  0.2299E+03
2.200  0.4034E+01  0.2303E+03
2.300  0.4071E+01  0.2307E+03
2.400  0.1592E+02  0.2323E+03
2.500  0.1043E+02  0.2334E+03
2.600  0.9686E+01  0.2343E+03
2.700  0.7500E+01  0.2351E+03
2.800  0.4397E+01  0.2355E+03

```

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