Question regarding 'cak.py' VASP output units (Bohr vs. Ångström)

[lakshan dissanayake]

Dear CALYPSO Development Team,

I am writing with a quick question about the 'cak.py' analysis script. I have been running calculations with Quantum ESPRESSO (ICode = 4) and using `cak.py` to analyze the results.

I noticed that the 'UCell_...vasp' files generated by the script seem to have lattice vectors in Bohr units. When I load these files into VASP or other visualization software, the cell volumes are very large, so I suspect I might be misunderstanding the intended workflow or missing a step.

I was looking at the 'cak.py' script and found the 'write_vasp' function. It seems to read the lattice matrix from the QE output (`l = cell[0].copy()`) and write it directly to the VASP file:

```python
def write_vasp(pdir, cell, no, sgdata, wori, wprim):
    ...
    l = cell[0].copy()
    ...
    f.write('1.0\n')
    for item in l:
        f.write("%12.7f %12.7f %12.7f\n" % tuple(item))
    ...
```

Since VASP expects Ångström units for the lattice vectors, I was wondering if a conversion factor should be applied to the 'l' variable here?

I just wanted to check if this is the intended behavior or if I might have missed a setting somewhere.

Best regards,

Lakshan Dissanayake
University of Colombo.

[296389682]

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