[Pw_forum] help... taking care of all symmetry operations

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.

```