ABINIT Discussion Forums

Dear all
I used abinit to calculated for monoclinic structure of PZT, Zr/Ti = 50/50
when I ran to find optimized structure, the code found error below
We used VCA calculation
This my input files
#Definition of the unit cell
acell 10.7962 10.7736 8.273
angdeg 90 90.5 90
spgroup 8
brvltt -1
#Definition of the atoms
natom 10
typat 1 1 3 3 2 2 2 2 2 2
xred
0.0000 0.0000 0.0000
0.5000 0.5000 0.0000
0.5310 0.0000 0.4410
0.0310 0.5000 0.4410
0.5430 0.0000 0.9100
0.0430 0.5000 0.9100
0.2880 0.2540 0.3890
0.2880 0.7460 0.3890
0.7880 0.7540 0.3890
0.7880 0.2460 0.3890
chkinp: ERROR -
Atoms number 3 and 4 are located at the same point of the unit cell
(periodic images are taken into account).
Action: change the coordinate of one of these atoms in the input file.
-P-0000
-P-0000 leave_new : decision taken to exit ...

How can I going


Best.
Abdulmutta

try it with brvltt -1. Are you sure there are only 5 atoms in the primitive unit cell? What is the stoichiometry of your sample?

Dear Prof.Josef W. Zwanziger
Thank you for your reply
I not sure in my system, there is 5 atom in unit cell because I found that in http://cst-www.nrl.navy.mil/lattice/
with space group number 8 monoclinic phase but there is some Pb(Zr0.52Ti0.48)O3, it shown 21 atom unit cell below
# COMMON INPUT DATA

#Definition of the unit cell
acell 10.7962 10.7735 8.273
angdeg 90 90.2 90
brvltt -1
chkprim 0

#Used for the generation of alchemical pseudoatoms
npsp 4
znucl 82 8 22 40
ntypat 3
ntypalch 1
mixalch 0.48 0.52
ixc 23

#Definition of the atoms
natom 21
typat 1 1 1 1 1 1 1 1 1 1 3 3 3 3 2 2 2 2 2 2 2
xcart
0.00000000 5.70957000 0.00000000 #Pb
-0.03595300 5.70957000 4.13635380 #Pb
0.00000000 0.00000000 0.00000000 #Pb
-0.03595300 0.00000000 4.13635380 #Pb
2.86102000 2.85478500 0.00000000 #Pb
2.82506700 2.85478500 4.13635380 #Pb
5.72204000 5.70957000 0.00000000 #Pb
5.68608700 5.70957000 4.13635380 #Pb
5.72204000 0.00000000 0.00000000 #Pb
5.68608700 0.00000000 4.13635380 #Pb
0.11545683 2.85478500 1.85805013 #Zr/Ti
2.97647683 5.70957000 1.85805013 #Zr/Ti
2.97647683 0.00000000 1.85805013 #Zr/Ti
5.83749683 2.85478500 1.85805013 #Zr/Ti
0.26230579 2.85478500 3.72520023 #O
1.63454065 4.31986066 1.54244633 #O
3.12332579 5.70957000 3.72520023 #O
1.63454065 1.38970934 1.54244633 #O
3.12332579 0.00000000 3.72520023 #O
4.49556065 4.24449434 1.54244633 #O
4.49556065 1.46507566 1.54244633 #O
The code ran to me but I got space group Pm (# 6); Bravais mP (primitive monocl.)
I want to space group Cm (# 8)
How can learn about it.

Best.
Abdulmutta

Dear Prof.Josef W. Zwanziger
This my input for monoclinic phase when I ran the code shown below
#Definition of the unit cell
acell 10.7773 10.7524 7.8024
angdeg 90 90.479 90
spgroup 8
brvltt -1
#chkprim 0
#Definition of the atoms
natom 10
typat 1 1 3 3 2 2 2 2 2 2
xred
0.0000 0.0000 0.0000
0.5000 0.5000 0.0000
0.5310 0.0000 0.4410
0.0310 0.5000 0.4410
0.5430 0.0000 0.9100
0.0430 0.5000 0.9100
0.2880 0.2540 0.3890
0.2880 0.7460 0.3890
0.7880 0.7540 0.3890
0.7880 0.2460 0.3890


chkinp: ERROR -
Atoms number 3 and 4 are located at the same point of the unit cell
(periodic images are taken into account).
Action: change the coordinate of one of these atoms in the input file.
-P-0000
-P-0000 leave_new : decision taken to exit ...

when I reject the spgroup the code can be ran to me
but I not sure my space group is Cm monoclinic phase
please look at my input how can I going

Best.
Abdulmutta

Dear all
For monoclinic phase of PZT that is near MPB region
and this is multiplicity and Wyckoff letter
Pb 2a 0.0 0.0 0.0
Zr/Ti 2a 0.477 0.0 0.551
O1 2a 0.449 0.0 0.099
O2 4b 0.212 0.257 0.627

but how can I found xred for atomic position in Cm space group number 8

Best.
Abdulmutta