The ABINIT Users Mailing List ( CLOSED )

[kdelaney@mrl.ucsb.edu]

Hi Marc,

The problem exists at least with versions 4.6.5 and 5.2.2; I tried with the 
precompiled binary distributions generated with IFC.

I tried to use five different PAW data with the same result. Three I 
generated myself, the other two were 6c_lda.paw and 8o.paw found in the 
Psps_for_tests directory of the abinit distribution. 

The problem is more severe for potentials with large augmentation 
contributions, hence C and O show the error but it is very subtle. The error 
is best visualized by running an SCF calculation followed by a non-SCF 
calculation with a subset of the original k-points. Then, comparing the 
eigenvalues directly, one can see differences that are too large for a 
convergence error. For potentials with large augmentation contributions 
(transition metals, rare earths) the band structure generated by a non-SCF 
calculation becomes very messy, while the eigenvalue spectrum from the SCF 
calculation looks sensible.

At the end of this post is an example input file that demonstrates the 
problem. It is a very basic input modified from the PAW1 tutorial on the 
abinit website. With this input, I used 6c_lda.paw and obtained the following 
eigenvalues for kpoint #2 (-0.125, 0.50, 0.00):
  
  band  | SCF eval (Ha) | non-SCF eval (Ha)
--------------------------------------------
    1   |  -0.39181     | -0.39786
    2   |  -0.31293     | -0.31258
    3   |  -0.11604     | -0.11586
    4   |  -0.09376     | -0.09357
...

As I commented in my previous post, the issue appears to stem from the 
augmentation data not being correctly initialized in the second calculation.

Thanks,
Kris.

--

ndtset 2

ecut 15.0
pawecutdg  35
nstep 30

acell 3*10.6
rprim 0.0 1/2 1/2
      1/2 0.0 1/2
      1/2 1/2 0.0

ntypat 1
znucl 6

natom 2
typat 1 1
xred
0.0 0.0 0.0
1/4 1/4 1/4

nband 22
prtwf 0

#SCF calculation
iscf1 13
occopt1 7
tsmear1 5.0d-3
prtden1 1
kptopt1 1
ngkpt1 4 4 4
nshiftk 4
shiftk 1/2 1/2 1/2
       1/2 0.0 0.0
       0.0 1/2 0.0
       0.0 0.0 1/2
toldfe1 1.0d-7

# non-SCF calculation 
iscf2 -2
getden2 -1
kptopt2 0
nkpt2 3
kpt2  -0.125 -0.25 0.0
      -0.125  0.50 0.0
      -0.250 -3/8  0.0
tolwfr2 1.0d-10
enunit2 1
prteig2 1