MCSQS correclation

Alloy Theoretic Automated Toolkit (ATAT)
1

Hello,

Because I have big convergence issues, im trying to implement a method for a more robust DFT calculation scheme for SQS.
My goal is to calculate several SQS between two endmembers, e.g. ABX – ACX with intermediate SQS of e.g. B=0.125, C=0.875; B=0.25, C=0.75; … ; B=0.875, C=0.125

I want to start with the boundaries (B=0.125, C=0.875) and go forth to the middle (B=0.5, C=0.5) while setting the earlier SQS as a new input structure. Therefore I would need the SQS to let the structure of the earlier SQS the same, but change another set of elements.

For explanation:

My first RNDSTR.in file (if we start at B=0.25, C=0.75) would look like that:
x x x A
x x x A
z z z B=0.25, C=0.75
z z z B=0.25, C=0.75
z z z B=0.25, C=0.75
z z z B=0.25, C=0.75

and the result may look like this:
x x x A
x x x A
y y y B
z z z C
z z z C
z z z C

To get now the next on top of the last one i would like to do:
x x x A
x x x A
y y y B
z z z B=0.333333, C=0.666666
z z z B=0.333333, C=0.666667
z z z B=0.333333, C=0.666667

To get:
x x x A
x x x A
y y y B
y y y B
z z z C
z z z C

Question: does mcsqs calculates the correlation between the fixed B and the mixing sites?

Thank you very much,
Peter.

2

No I don’t think you should have a fixed B while generating an SQS, unless you don’t want include any correlation of that fixed B (I don’t think you would like to exclude that in your study).

If you would like to exclude that, you can simply replace the "B"s with “a_B” and “b_B” for fixed ones and unfixed ones. Then mcsqs would only calculate the correlation of unfixed B and C.