Impossible to match point correlations due to incompatible s

Alloy Theoretic Automated Toolkit (ATAT)
1

Hello Everyone,
I am new to ATAT-SQS structure. I am trying to generate the SQS structure for a quinary alloy system of BCC structure with 128 atoms. In the rndstr.in file, i assigned A=0.2, B=0.2, C=0.2, D=0.2, E=0.2. But it doesnt generate the SQS structure due to this error "Impossible to match point correlations due to incompatible supercell size".
Note: I was able to generate SQS structure for binary alloys using A=0.5, B=0.5 in the rndstr.in file.

If anyone has experienced this kind of issue before and found the solution, I would greatly appreciate it.

2

This makes sense to me, can you try 0.203125 instead of 0.2 for each element except one and for the one make it (1 - sum of compositions of others )

3

thank you humashankar, if I tried 0.203125 for each element as you suggested, the error I got is "Probabilities must sum to 1.". It still showed the same error if I tried it for 0.203125 for 4 elements instead of 5 elements.

Please, what can I do next.

4

Hi, I am trying to generate 16 atom SQS for FCC Cr3Al alloy (A3B) in the stoichiometry Cr0.75Al0.25. The following is my input file (rndstr.in):
1 1 1 90 90 90
0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0
0.00 0.00 0.00 Cr=0.5,Al=0.5
0.50 0.50 0.50 Cr=0.5,Al=0.5
0.25 0.25 0.25 Cr=0.5,Al=0.5
0.75 0.75 0.75 Cr=0.5,Al=0.5

In the appendix of this link:https://dunand.northwestern.edu/refs/files/wolverton.pdf, the author has given the lattice vectors and positions. May I know if it is the input or a generated SQS output? Actually I am trying to reproduce the same output but my output looks something like follows:
1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
-1.000000 -0.500000 -0.500000
0.000000 0.500000 0.500000
0.000000 1.000000 -1.000000
-0.500000 0.500000 0.000000 Al
-1.000000 1.000000 -1.000000 Cr
-0.500000 1.000000 -0.500000 Cr
-1.000000 0.500000 -0.500000 Al
-1.000000 -0.000000 -0.500000 Al
-0.500000 1.000000 -1.000000 Al
-1.000000 0.500000 -1.000000 Cr
-0.500000 0.500000 -0.500000 Cr
-0.250000 0.250000 -0.250000 Al
-0.750000 0.750000 -1.250000 Al
-0.250000 0.750000 -0.750000 Cr
-0.750000 0.250000 -0.750000 Cr
-0.750000 0.250000 -0.250000 Cr
-0.250000 1.250000 -0.750000 Al
-0.750000 0.750000 -0.750000 Al
-0.250000 0.750000 -0.250000 Cr

Can you also let me know if my input is correct or not, and can you please provide your input files for A=0.5,B=0.5 (A3B)alloy?

5

Keep in mind that there may be more than 1 SQS that satisfies given correlation constraints. Also, mcsqs generates SQS using a stochastic algorithm, so the same output is definitely not always obtained for the same input.