My Community

Dear all,
I am doing the density of states of Al systems. The density of states looks very spiky.
Here is the INCAR file that I have:

!---general---
SYSTEM = Al-X
!
!---Startparameter_for_this_run---
PREC = High !Normal,Medium,High,Low
ISTART = 0 !WAVECAR:0-new,1-cont,2-samecut
ICHARG = 11 !charge:1-file,2-overlapping_atom,10-const
LORBIT = 11

!
!---spin_calculation---
ISPIN = 1
!
!---Electronic_Relaxation1---
ENCUT = 420
LREAL = .FALSE. !F:small_syst,T:large
NBANDS = 40
NELM = 130
NELMIN = 4 !min_nb_ELM
NELMDL = -2 !nb_ELM_before_charge_update
EDIFF = 1e-6 !stopping-criterion_for_ELM [eV]
NGX = 40
NGY = 40
NGZ = 40
EMIN = -2.3
EMAX = 44.2
NEDOS = 16000

!
!---DOS_related_values---
ISMEAR = -5
! ISMEAR:tetrahedron,-1:fermi,0:Gaussian,N:Methfessel-Paxton(Metal)
SIGMA = 0.4 !smearing_width_ISMEAR
!
!---Electronic_relaxation2----
ALGO = FAST
!---Parallel_processing
LPLANE = .TRUE.
NPAR = 4
!---Write_flags---
LWAVE = F !write_WAVECAR
LCHARG = F !write_CHGCAR
LVTOT = F !write_LOCPOT,local_potential
LELF = F !write_electronic_localiz_function(ELF)

And this is the KPOINTS file:
K-Points
0
Gamma
40 40 40
0 0 0

Thank you very much in advance!
Riche

The answers to the following questions may clear my doubts also:
(1) Without relaxation, ISMEAR=1 makes DOS smoother than ISMEAR=-5. But can I trust the results with ISMEAR=1.
(2) what kind of KPOINTS files should I use? Explicit input or automatically generated. What is the consequence if I use automatically generated k-points?
(3) Is it absolutely necessary to set ISYM to be 0?

First of all, you must ALWAYS relax the system first BEFORE doing a DOS calculation. Once you have obtained the ground state structure, you go back and run a DOS calculation. ISMEAR = -5 may make the DOS look more spikey, but should smooth out if you increase NEDOS. It doesn't matter which k-point generation scheme you use as long as you have enough k-points. If you use auto you can see in the OUTCAR file what your grid/mesh is. ISYM = = 0 switches off symmetry. It depends on the symmetry of your system as to whether this will matter or not, but it never hurts just to switch it off.

Dear panda,
Thank you very much for your reply.
As you may see, I set NEDOS to be 16000 in INCAR. Previously I used NEDOS=8000. Even NEDOS=16000 does not help a bit. The energy step is like 3 meV when NEDOS=16000. But anyway, I will try it again with the smaller or much smaller energy step. And see what comes out.