bug in integrated DOS for fixed moment
Posted: Fri Jan 20, 2006 7:11 pm
Dear VASP users,
I did a fixed moment calculation ( NUPDOWN= 6 Bohr magneton/supercell; total energy self-consistent, but magnetic moment per cell is not changed from iteration to iteration) for a system having NELECT=1010 ( a supercell containing 250 atoms).
After self-consistent run, I used ICHARG=1 and copied CONTCAR to
POSCAR, NSW= 0. LORBIT=10 to get the DOS.
In the DOSCAR file the first block has 5 coloumns: energy, upDOS, dnDOS, integratedUP and integratedDN
But the integarated UP and DOWN DOS numbers upto Fermi energy are wrong. They donot add up to total number of electrons in the
supercell ie NELECT =1010 and their difference is not NUPDOWN =6.
The NON-FIXED MOMENTcalculation DOS for the SAME system do not have such behavior. It correctly adds upto NELECT=1010 and their difference is what is obtained per cell after fully self-consistent calculation.
I show here ONLY a piece of data from the DOSCAR file of FIXED MOMENT calculation near FERMI ENERGY( which is 6.0796 eV):
5.750 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.775 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.800 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.825 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.850 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.875 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.900 0.2068E+02 0.0000E+00 0.1014E+04 0.1000E+04
5.925 0.3349E+02 0.0000E+00 0.1015E+04 0.1000E+04
5.950 0.9714E+01 0.0000E+00 0.1015E+04 0.1000E+04
5.975 0.4546E+01 0.1105E+02 0.1016E+04 0.1000E+04
6.000 0.3595E+01 0.5060E+02 0.1016E+04 0.1001E+04
6.025 0.2329E+02 0.7827E+01 0.1016E+04 0.1002E+04
6.050 0.2321E+02 0.1955E+02 0.1016E+04 0.1002E+04
6.075 0.1848E+02 0.6314E+02 0.1017E+04 0.1004E+04
6.100 0.4671E+02 0.3709E+02 0.1018E+04 0.1005E+04
As one can see (from 3rd and 4th coloumn), the sum of integrated up and down is not 1010 at Fermi energy (6.075 eV) and their difference is not 6. Since I am doing a fixed moment
calculation with NUPDOWN =6 and NELECT in OUTCAR file is 1010, isn't the integrated UP and DOWN add to NELECT= 1010
upto FERMI energy and their difference upto Fermi energy should be 6?
Pl. note I don't get this behavior for NON-FIXED MOMENT calculations with the SAME SYSTEM (NELECT =1010).
The INCAR file used to calculate DOSCAR:
(CHGCAR and CONTCAR from the previous run was used here
with NSW =0 and LORBIT=10)
SYSTEM = fixedmoment
Start parameter for this Run:
ICHARG = 1
ISPIND = 2
ISPIN = 2
NUPDOWN = 6
PREC = high
Electronic Relaxation
ENCUT = 340.0000
NELMIN = 5
NELM = 90
EDIFF = 1E-05 stopping-criterion for ELM
ISYM = 2
DOS related values:
ISMEAR = -5
NEDOS = 1201
EMIN = -15.0
EMAX = 15.0
LORBIT = 10
IALGO = 48
LREAL = O
Is my understanding wrong, OR I am doing something wrong
OR is there a really bug in the code for integrated up and down
DOS fixed moment calcuation.
Which piece of the code calculate the integrated DOSUP and integreated DOSDN numbers?
Sahu
I did a fixed moment calculation ( NUPDOWN= 6 Bohr magneton/supercell; total energy self-consistent, but magnetic moment per cell is not changed from iteration to iteration) for a system having NELECT=1010 ( a supercell containing 250 atoms).
After self-consistent run, I used ICHARG=1 and copied CONTCAR to
POSCAR, NSW= 0. LORBIT=10 to get the DOS.
In the DOSCAR file the first block has 5 coloumns: energy, upDOS, dnDOS, integratedUP and integratedDN
But the integarated UP and DOWN DOS numbers upto Fermi energy are wrong. They donot add up to total number of electrons in the
supercell ie NELECT =1010 and their difference is not NUPDOWN =6.
The NON-FIXED MOMENTcalculation DOS for the SAME system do not have such behavior. It correctly adds upto NELECT=1010 and their difference is what is obtained per cell after fully self-consistent calculation.
I show here ONLY a piece of data from the DOSCAR file of FIXED MOMENT calculation near FERMI ENERGY( which is 6.0796 eV):
5.750 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.775 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.800 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.825 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.850 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.875 0.0000E+00 0.0000E+00 0.1014E+04 0.1000E+04
5.900 0.2068E+02 0.0000E+00 0.1014E+04 0.1000E+04
5.925 0.3349E+02 0.0000E+00 0.1015E+04 0.1000E+04
5.950 0.9714E+01 0.0000E+00 0.1015E+04 0.1000E+04
5.975 0.4546E+01 0.1105E+02 0.1016E+04 0.1000E+04
6.000 0.3595E+01 0.5060E+02 0.1016E+04 0.1001E+04
6.025 0.2329E+02 0.7827E+01 0.1016E+04 0.1002E+04
6.050 0.2321E+02 0.1955E+02 0.1016E+04 0.1002E+04
6.075 0.1848E+02 0.6314E+02 0.1017E+04 0.1004E+04
6.100 0.4671E+02 0.3709E+02 0.1018E+04 0.1005E+04
As one can see (from 3rd and 4th coloumn), the sum of integrated up and down is not 1010 at Fermi energy (6.075 eV) and their difference is not 6. Since I am doing a fixed moment
calculation with NUPDOWN =6 and NELECT in OUTCAR file is 1010, isn't the integrated UP and DOWN add to NELECT= 1010
upto FERMI energy and their difference upto Fermi energy should be 6?
Pl. note I don't get this behavior for NON-FIXED MOMENT calculations with the SAME SYSTEM (NELECT =1010).
The INCAR file used to calculate DOSCAR:
(CHGCAR and CONTCAR from the previous run was used here
with NSW =0 and LORBIT=10)
SYSTEM = fixedmoment
Start parameter for this Run:
ICHARG = 1
ISPIND = 2
ISPIN = 2
NUPDOWN = 6
PREC = high
Electronic Relaxation
ENCUT = 340.0000
NELMIN = 5
NELM = 90
EDIFF = 1E-05 stopping-criterion for ELM
ISYM = 2
DOS related values:
ISMEAR = -5
NEDOS = 1201
EMIN = -15.0
EMAX = 15.0
LORBIT = 10
IALGO = 48
LREAL = O
Is my understanding wrong, OR I am doing something wrong
OR is there a really bug in the code for integrated up and down
DOS fixed moment calcuation.
Which piece of the code calculate the integrated DOSUP and integreated DOSDN numbers?
Sahu