SQS Generation for HCP TiAlV Alloy and DFT Convergence Issues

Alloy Theoretic Automated Toolkit (ATAT)
1

Dear ATAT Community,
I am working on generating a Special Quasirandom Structure (SQS) for a TiAlV alloy with (90% Ti, 6% Al, 4% V) in an HCP crystal structure using the mcsqs tool from ATAT. Despite following the documentation and an example from (Redirecting), I am encountering two issues and would appreciate your guidance.

  1. Uncertainty About HCP Sublattices
    The article’s example (Table 1) defines two sublattices for an HCP structure, and below is my run rndstr.in
    3.0 3.0 5.0 90 90 120 # Hexagonal lattice parameters (a, b, c, α, β, γ)
    1 0 0 # Primitive lattice vectors
    0 1 0
    0 0 1
    0 0 0 Ti=0.9,Al=0.06,V=0.04 # Sublattice 1
    0.6666666667 0.3333333333 0.5 Ti=0.9,Al=0.06,V=0.04 # Sublattice 2
    with:
    corrdump Command
    corrdump -l=rndstr.in -ro -noe -nop -clus -2=6 -3=5.2 -4=5.2

mcsqs Command
mcsqs -n=100 -wr=1 -T=1 -ip=1

2- DFT Convergence Issues
After generating SQS supercells (50 and 100 atoms), I ran DFT calculations in Quantum Espresso, but the simulations did not converge.

Could someone share a working example for ternary HCP SQS (prefer TiAlV )?
Are there known best practices for corrdump/mcsqs in ternary systems?
How can I debug DFT convergence issues linked to SQS?

2

The HCP only has one sublattice. The two atomic sites are symmetry equivalent.

Did you check your atomic structure after mcsqs? If you have a reasonable structure, you need to check your settings for the DFT calculations.