primitive cell of bcc

Alloy Theoretic Automated Toolkit (ATAT)
1

Dear all,
I have a problem understanding the primitive cell of the bcc structure. As we can see from the example diretory of atat that the bcc_lat.in of bcc is in the following format:
1 1 1 90 90 90
0.5 0.5 0.5
0.5 -0.5 0.5
0.5 0.5 -0.5
0 0 0 A
and the corresponding lattice parameters, a,b,c,alpha,beta,gamma
is 0.86603 0.86603 0.86603 109.47122 70.52878 70.52878
but i also found that the primitive cell of the bcc would be:
1 1 1 90 90 90
-0.5 0.5 0.5
0.5 -0.5 0.5
0.5 0.5 -0.5
0 0 0 A
and the corresponding lattice parameters, a,b,c,alpha,beta,gamma:
0.86603 0.86603 0.86603 109.47122 109.47122 109.47122
I donot know whether they may result in different sqs structures.

Regards,

wzchen

2

Both unit cells are valid.
The same (up to symmetry transformations) SQSes would be generated.
Of course, if you use mcsqs (which I suggest), the output is determined by some random numbers too, so different runs may give different outputs, but not because of unit cell differences.

3

Thanks :smiley: