DOS calculation of NiO using LDA (without PAW)

[lamsalc]

Hi everybody
I am a new user of Abinit and I am trying to get DOS for NiO. I added following lines
prtdos 3 natsph 4 iatsph 1 2 3 4 ratsph 3.1 3.1 2.8 2.8
to the input file "tldau_3.in". But I got weird graph as shown.
I will be grateful if some body help me in this regard.
Thank you,
lamsalc

[jolafc]

Hi,

If you modified the tldau_3.in file as you stated, I assume you obtained this .in :

Code: Select all

#Spin
nsppol 1
nspden 2
nspinor 1
spinat 0 0 1
       0 0 -1
       0 0 0
       0 0 0

#Parameters
nstep  50
ecut 15
pawecutdg 30
iscf 17
toldfe 1.0d-5
nband  40
occopt 1
#tsmear 300 K

#Structural parameters
natom 4
ntypat 2
typat 1 1 2 2
znucl 28 8
xred 0 0 0
    0.0 0.0 0.5
    0.5 0.5 0.25
    0.5 0.5 0.75

acell   3*7.92

rprim 0.0 1/2 1/2
      1/2 0.0 1/2
      1.0 1.0 0.0

# Kpoint Grid
ngkpt 2 2 2
chksymbreak 0  # The k point grid is not symmetric, but the calculations being for the ground-state, this is not a problem.

# LDA+U
usepawu   1
lpawu   2 -1
upawu  8.0 0.0 eV
jpawu  0.8 0.0 eV

#Density matrix
usedmatpu 5

dmatpawu
#Occupation matrix for spin  1 and atom 1
     0.90036    0.00000   -0.00003    0.00000    0.00000
     0.00000    0.90036   -0.00001    0.00000    0.00002
    -0.00003   -0.00001    0.91309   -0.00001    0.00000
     0.00000    0.00000   -0.00001    0.90036   -0.00002
     0.00000    0.00002    0.00000   -0.00002    0.91309
#Occupation matrix for spin  1 and atom 2
     0.89677   -0.00001    0.00011   -0.00001    0.00000
    -0.00001    0.89677    0.00006    0.00001   -0.00010
     0.00011    0.00006    0.11580    0.00006    0.00000
    -0.00001    0.00001    0.00006    0.89677    0.00010
     0.00000   -0.00010    0.00000    0.00010    0.11580
# add to conserve old < 6.7.2 behavior for calculating forces at each SCF step
 optforces 1

prtdos 3
natsph 4
iatsph 1 2 3 4
ratsph 3.1 3.1 2.8 2.8

This calculation is (as tests should be) quite underconverged on many aspects to allow the test to run in a few seconds on a single processors. If you want meaningful results, several points need to be corrected :

1) The cutoff energies are too low. For Nickel, the values

Code: Select all

ecut 15
pawecutdg 30

should be replaced by

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ecut 30
pawecutdg 60

2) The tolerance on the total energy is high.

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toldfe 1.0d-5

should be replaced by

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toldfe 1.0d-7

(or less, but it can get difficult for an antiferromagnetic calculation)

3) Most importantly, you should use a muh finer k-point grid. Replace :

Code: Select all

ngkpt 2 2 2

by (at least) :

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ngkpt 8 8 4

and then, continue to converge this parameter to higher values.

Good luck!

Jonathan Laflamme Janssen

[lamsalc]

Hi
Thank you very much for the reply.