ABINIT Discussion Forums

HI,
I have been trying to treat a cluster of 13 gold atoms as single molecule i.e as a single k-point. But if I select kptopt 1 and nkpt 1 ; it always gives me an error message
getkgrid.F90:446:BUG
The argument nkpt= 1, does not match
the number of k points generated by kptopt, kptrlatt, shiftk,
and the eventual symmetries, that is, nkpt= 4.
However, note that it might be due to the user,
if nkpt is explicitely defined in the input file.
In this case, please check your input file.
Action : contact ABINIT group.

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1) How can I include my cluster of 13 atoms as a single entity? If anyone could point out what am I doing incorrectly in the input file, I would appreciate the help. But when I comment out nkpt 1 the job runs fine, but it takes 4 k-points which i do not want to happen.

following is my input file;
ionmov 3 # Use the modified Broyden algorithm
ntime 10 # Maximum number of Broyden "timesteps"
tolmxf 5.0d-4 # Stopping criterion for the geometry optimization : when
# the residual forces are less than tolmxf, the Broyden
# algorithm can stop
#nsym=1 #nosymmetry

#starting value of the
#atomic coordinates
xangst 0.000000 0.000000 0.000000
0.849720 1.069510 2.492360
-2.491980 -1.263910 -0.196890
2.502080 1.253390 0.209750
-0.848840 -1.068710 -2.494550
-0.024370 2.889930 0.133860
1.974360 -1.593130 1.393900
-1.975910 1.613340 -1.381670
0.029030 -2.880950 -0.147810
-0.875280 -1.401910 2.339300
2.079160 -1.113220 -1.624250
-2.082130 1.116450 1.628250
0.857510 1.406510 -2.336120

toldff 5.0d-5 # Will stop the SCF cycle when, twice in a row,
# the difference between two consecutive evaluations of
# forces differ by less than toldff (in Hartree/Bohr)
#toldfe 1.0d-6
#------------------------------------------------------------------------------
#Definition of the unit cell
acell 8 8 8 angstroms # The keyword "acell" refers to the
# lengths of the primitive vectors (in Bohr)
#rprim 1 0 0 0 1 0 0 0 1 # This line, defining orthogonal primitive vectors,
# is commented, because it is precisely the default value of rprim

#Definition of the atom types
ntypat 1 #2 types of atom
znucl 79

#Definition of the atoms
natom 13 # There are 13 atoms
typat 1 1 1 1 1 1 1 1 1 1 1 1 1 #

#Definition of the planewave basis set
ecut 20.0 # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
kptopt 1 # Enter the k points manually
nshiftk 1
shiftk 0.5 0.5 0.5
#nkpt 1 # Only one k point is needed for isolated system,
# taken by default to be 0.0 0.0 0.0 So when I comment this it runs fine !!!! *
ngkpt 2 2 2
Chksymbreak 0

#Definition of the SCF procedure
nstep 200 # Maximal number of SCF cycles
#toldfe is no more defined, as toldff is used above...
diemac 2.0 # Although this is not mandatory, it is worth to
# precondition the SCF cycle. The model dielectric
# function used as the standard preconditioner
# is described in the "dielng" input variable section.
# Here, we follow the prescriptions for molecules
# in a big box


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2) but when it runs , it does not convergers, (but ofcourse i can increase SCF cycles ) But my biggest concern is after 50 runs the icosahedral structure for the 13 atoms is lost.
I've been using Troullier-Martins pseudopotentials for my calculations , so is there any reliable pseudopototentials for gold ?

Thank you very much

Dude, use kptopt 0, not kptopt 1. Then you can use nkpt 1 and it should run fine. Read the documentation, homie. In fact, there's actually a tutorial (for running parallel jobs) that treats a gold cluster like you are doing. It might be worth taking a look at. You should find it in your tests/paral/Input directory where you installed abinit. good luck.