ABINIT Discussion Forums

Dear all
Please help me , when I compute optimized structure of rhombohedral phase
I have bug files.
and this is my input files
# PbTiO3 : computation of the total energy
# pure of Ti.
ndtset 15
acell: 7.10 7.10 7.10
acell+ 0.10 0.10 0.10

#Definition of the basis of the geometry relaxation, the volume of the cell is fixed.
optcell 3
ionmov 2
dilatmx 1.2
ecutsm 0.5

# COMMON INPUT DATA

#Definition of the unit cell
angdeg 89.91023363 89.91023363 89.91023363

#Definition of the atom types
ntypat 3
znucl 82 22 8

#Definition of the atoms
natom 5
typat 1 2 3 3 3
xred
0.0 0.0 0.00
0.5 0.5 0.50
0.5 0.5 0.00
0.0 0.5 0.50
0.5 0.0 0.50

#Definition of the planewave basis set
ecut 25.0
pawecutdg 35
pawovlp -2
# find the optimal total energy
ntime 100
tolmxf 1.0d-5
toldff 1.0d-6

#Definition of the k-point grid
kptopt 1
ngkpt 6 6 6
nshiftk 1
shiftk
0.5 0.5 0.5

#Definition of the SCF procedure
nstep 100
#toldfe 1.0d-6
diemac 6
##############################################################
I found bug file in log file
BROYDEN STEP NUMBER 75 ------------------------------------------------------
Unit cell characteristics (before scfcv) :
acell= NaN NaN NaN
rprim= NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
ucvol= NaN Bohr^3

xred=
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
-P-0000 leave_test : synchronization done...
Cartesian coordinates (bohr)
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
NaN NaN NaN
Cartesian forces (hart/bohr); max,rms= 0.00000E+00 0.00000E+00 (free atoms)
-0.00000000000000E+00 -0.00000000000000E+00 -0.00000000000000E+00
-0.00000000000000E+00 -0.00000000000000E+00 -0.00000000000000E+00
-0.00000000000000E+00 -0.00000000000000E+00 -0.00000000000000E+00
-0.00000000000000E+00 -0.00000000000000E+00 -0.00000000000000E+00
-0.00000000000000E+00 -0.00000000000000E+00 -0.00000000000000E+00


iter Etot(hartree) deltaE(h) residm nres2 diffor maxfor

FFT (fine) grid used in SCF cycle:

bound: BUG -
Trouble finding boundary of G sphere for
kpt= 0.0000 0.0000 0.0000 and ng= 48 48 48
Action : check that kpt lies reasonably within first Brillouin zone;
else code bug, contact ABINIT group.
Action : contact ABINIT group.

.Delivered 300 WARNINGs and 75 COMMENTs to log file.
-P-0000
-P-0000 leave_new : decision taken to exit ...

Best.
Abdulmutta

Looks like something went wrong during the relaxation process.
- Is the total energy decreasing along the broyden steps ?
- Do the position of you atoms looks "sensible" at step 74 ?
- What happens if you try to restart your job from the cell parameters of step 74 ?

Dear sir
I don't understand , so I beginner for abinit
please tell me about it more details
How I going now

Best
Abdul.

1- If I'm not wrong, you are trying to relax your structure, that is find the most accurate cell parameters (rprim+xred) for your compound with respect to your calculation parameters (cutoff energy, kpt sampling, pseudo-potentials, etc).
The algorithm you use for this is called Broyden. More or less, at each "broyden step" you should get some cell parameters that are closer to the optimal cell parameters. One way to check this is to follow the evolution of total energy along the broyden steps. From step to step, the converged total energy should get smaller and smaller.
2- Supposing you didn't made a large mistake, the relaxed parameters should stay close to your initial parameters. If you observe a very large variation of any parameter it could be a nice clue to guess what is going on your calculation.
3- Look at your output file. Take the value therein at broyden step 74 for the relaxed cell parameters and copy them in you input file (in place of your initial input). Then run again Abinit and see what is happening...