[Pw_forum] help... taking care of all symmetry operations
Mousumi Upadhyay
mousumi at jncasr.ac.in
Tue Mar 9 07:49:03 CET 2004
Hi,
I want to know, how all the symmetry operations for my systems
can be taken care of, through PWSCF?
I'm sending the following warning part,
""
input
warning: symmetry operation # 7 not allowed. fractionary
translation:
0.0000000 0.0000000 0.3333333 in crystal coordinates
warning: symmetry operation # 8 not allowed. fractionary
translation:
0.0000000 0.0000000 -0.3333333 in crystal coordinates
warning: symmetry operation # 11 not allowed. fractionary
translation:
0.0000000 0.0000000 -0.3333333 in crystal coordinates
warning: symmetry operation # 12 not allowed. fractionary
translation:
0.0000000 0.0000000 0.3333333 in crystal coordinates""
But in our system, in a unit cell, three atoms are in
three different levels, 0, 1/3 & 2/3. So, this must be taken care of
to get relaxed reduced co-ordinates.
For example, starting at some lattice constant value,
with reduced co-ordinate,
2.16500000000E-01 0.0000000000E+00 -1.8503717077E-17 1
-2.16500000000E-01 -2.16500000000E-01 3.3333333333E-01 1
0.0000000000E+00 2.16500000000E-01 6.6666666667E-01 1
final reduced co-ordinates, we got as,
0.208561119 0.000000000 0.000000000 1
-0.206588002 -0.204614884 0.336091984 1
-0.001973118 0.204614884 0.663908016 1
The values, 0.2085, 0.2065, 0.2046 are all expected to be same atleast
upto 4th deecimal places. I believe this discripency is because, all
symmetry operations are not taken care of. So, how can we get rid of that
in PWSCF??? By which input parameter?
Best regards, Mousumi.
More information about the Pw_forum
mailing list