The theory is only exactly correct for integer thicknesses, but it might be useful to have a way to disable the enforcing to integer thicknesses to explore if smaller thickness steps are helpful for fitting experimental data.
As a side note: Alternative ways to obtain smaller thickness steps could be using a smaller unit cell extension along 001 direction which might be often possible if laterally shifted atomic position patterns repeat along 001. Or one can use the Darwin theory implementation which however is more complicated to implement for the user.
The theory is only exactly correct for integer thicknesses, but it might be useful to have a way to disable the enforcing to integer thicknesses to explore if smaller thickness steps are helpful for fitting experimental data.
As a side note: Alternative ways to obtain smaller thickness steps could be using a smaller unit cell extension along 001 direction which might be often possible if laterally shifted atomic position patterns repeat along 001. Or one can use the Darwin theory implementation which however is more complicated to implement for the user.