Shifting of bands towards negative energy in band structure calculations.

[deepika]

Dear Sir,
We are doing band structure calculations for graphene nano ribbons (1-D). While performing non_sc calculations using ICHARG= 11 tag, bands are shifted toward negative energy but the bands are at accurate positions (as in the literature) while using ICAHRGE= 0 tag. Shifting of bands is around -2 eV toward valence band. CHGCAR from sc is used with ICARGE = 11 tag.

[deepika]

Dear Sir,

The INCAR files used to find the band st. of 5-ZGNR with hydrogen terminated is as follow:

INCAR for relaxation.
# Basic setup:
SYSTEM = Relax GNR
ISTART = 0
ICHARGE = 2
ISMEAR = 1
SIGMA= 0.1
EDIFF = 0.000001
EDIFFG = -0.001
PREC = HIGH
LWAVE = .TRUE.
LCHARGE = .TRUE.
LVTOT = .FALSE.
ENCUT = 300
ISIF = 2
IBRION = 2
NSW = 100


INCAR for sc
# Basic setup:
SYSTEM = Graphene
ISTART = 0
ICHARGE = 2
ISMEAR = -5
EDIFF = 0.00000001
PREC = HIGH
LWAVE = .FALSE.
LCHARGE = .TRUE.
LVTOT = .FALSE.
ENCUT = 300
IBRION = -1
NSW = 0


INCAR for non_sc
# Basic setup:
SYSTEM = Graphene nano ribbon
ISTART = 0
ICHARGE = 11
ISMEAR = 0
SIGMA= 0.01
EDIFF = 0.00000001
EDIFFG = -0.005
PREC = HIGH
LWAVE = .FALSE.
LCHARGE = .TRUE.
LVTOT = .FALSE.
LREAL = .TRUE.
ENCUT = 300
IBRION = -1
NSW = 0
IALGO = 48
NELM = 40
NELMIN = 8

For plotting of band structures, we have used P4Vasp tool