ABINIT Discussion Forums

Dear All,
I am running Abinit 6.6.2 on a Mac Pro under OSX 10.6.7. I would like to calculate a single energy point using a Bi2Se3 reduced cell. However, Abinit informs me that the unit cell is not primitive and has a multiplicity of 3 (chkprimit : ERROR -). This seems strange since I am using the definition of a primitive cell given in the Pearson Tables. Bi2Te3 belongs to space group 166, therefore I set the basis to Hexagonal with spgaxor=1.

I have copied my input file and the log's error message below. I would be grateful if anybody can help me with this.

Kind Regards,
Rob Simpson

ERROR MESSAGE
===============
chkprimit : ERROR -
According to the symmetry finder, the unit cell is
NOT primitive. The multiplicity is 3 .
The use of non-primitive unit cells is allowed
only when the input variable chkprim is 0.
Action : either change your unit cell (rprim or angdeg),
or set chkprim to 0.
-P-0000
-P-0000 leave_new : decision taken to exit ...

INPUT FILE
=========

# Bi2Se3
# Energy cutoff convergence study for zero point energy

ndtset 5 # number of data sets

ionmov 0 # do not move atoms - single point energy calc
nstep 50 # maximum number of scf steps
ntime 500 # Maximum number of optimization steps
tolmxf 5.0d-5 # Optimization is converged when maximum force
# (Hartree/Bohr) is less than this maximum

ecutsm 0.5 # Energy CUToff SMearing

#=================================================
# Structure

spgroup 166 #Space Group (1=p1)
spgaxor 1 #space group 166 can be define as Rhombohedral (2) or Hex (1)-- need to specify hex

natom 3
ntypat 2 #number of types of Atoms
znucl 34 83 #Z-number of atom types Ge32, Sb51, Te52
typat 1 2 1 #typat is an array to label the atoms

acell 4.1345 4.1345 28.63620 Angstr #lengths of vectors to describe unit cell
angdeg 90 90 120 #ang(1) between 2nd and 3rd vectors, ang(2)

xred #better to define as fractions for accuracy. Also some atoms will be repeats due to symmetry translations
0 0 0.0000
0 0 0.4008
0 0 0.2117

#=================================================
# KptGrid which was found from the k-point study above
kptopt 1
ngkpt5 8 8 8
ngkpt4 7 7 7
ngkpt3 6 6 6
ngkpt2 4 4 4
ngkpt1 2 2 2
shiftk 5.0000E-01 5.0000E-01 5.0000E-01
#=================================================

getxred -1 # Start with relaxed coordinates from dataset D.S
getwfk -1 # Start with wave functions from previous D.S

ixc 11 # choice of exchange correlation i.e. LDA (paul uses 7, castep 2 but need to pseudo pots)
ecut 12
dilatmx 1.05 # Maximum scaling allowed for lattice parameters

occopt 3 # Smearing of Bands
tsmear 0.001 Ha # Temperature of Smearing, 0.001 Ha = 27.2113845 meV = 315.773 Kelvin
diemix 1 # Dielectric Mixing Factor
diemac 9 # model DIElectric MACroscopic constant
iscf 7 # Integer for Self-Consistent-Field cycles (7 pulay mixing)
npulayit 7 # Number of PULAY ITerations for SC mixing
#iprcel 45 # SCF preconditioning, compute the RPA dielectric matrix at the first step, and recompute each step
#toldff 5.0d-5 # TOLerance on the DiFference of force for stopping SCF, d is the same as 10 to the power of but means double precision
tolvrs 1.0d-12 # Tolerence for stopping SCF
#=================================================

Hi Rob,

Probably same discussion as in http://forum.abinit.org/viewtopic.php?f=8&t=944 and http://forum.abinit.org/viewtopic.php?f=8&t=843&start=0

Kind regards,

Alain

Thanks Alain. Sorry for the late reply- my attention has been diverted recently. Those posts seemed to solve the problem.