The ABINIT Users Mailing List ( CLOSED )

[Enrico <enrico.avenati@yahoo.com>]

Hi,
i've done some relaxation on ( optcell=2 Volume and atomic position) Ni FCC.
And i got very big difference in lattice parameter; in lDA 48% of the original
value!
In GGA 40,3%. 

I did some other FCC like La FCC and LaNi2 in LDA and again i noticed this 
huge
variation!

Instead using ALWAYS THE SAME OPTIMIZATION parameters I did LaNi5 ( in LDA) 
and
i got only 3,1% on a and 3,3% on c, which is more what LDA should do.

My PSEUDO in LDA are HGH WITHOUT SEMICORE only 10 electroins. 

I've just noticed the same variation in GGA with ixc=11 on Ni using
28-Ni.GGA.fhi pseudo.

Could tell me where i'm wrong?  

Tahnk you 
                    ENRICO

here follows the INPUT FOR Ni, I use to copy and paste the Relax part of the
input.

#UNIT CELL Ni

acell 3*3.5232 Angstr
rprim  0.0  0.5  0.5   # FCC Real space PRIMitive translations
       0.5  0.0  0.5 
       0.5  0.5  0.0
ntypat 1
znucl  28
natom  1  # atom per cell
typat  1  
xred
0.0 0.0 0.0

#GEOM OPTIMISATION
optcell 2   # optimisation of volume & ...
ionmov  3   # conduct structural optimization using the
Broyden-Fletcher-Goldfarb-Shanno minimization (BFGS),
            #   modified to take into account the total energy as well as the
gradients (as in usual BFGS)
ntime  30
dilatmx 1.09   # the maximal permitted scaling of the lattice parameters when
the cell shape and dimension is varied 
ecutsm  0.5    # Using a non-zero ecutsm, the total energy curves as a 
function
of ecut, or acell,
                 can be smoothed, keeping consistency with the stress

#RECIPROCAL SPACE INTEGRETION
kptopt 1
nshiftk 4            # shiftk=4 particular efficient for FCC 
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5
ngkpt 8 8 8
nband 19
tsmear 0.02
occopt 4

#PLANE WAVES
ecut 140

#SCF PROCEDURE
nstep 150
ixc 1
toldfe 1.0d-7