[Spglib-users] Bug in symmetry detection in spglib 1.15

[Lorenzo M. <mes...@gm...>]

Dear developers,

I think I found a bug that is affecting the newest version of spglib 
(version 1.14 works), or at least the python interface.

When I ask the symmetry group of a structure by with a python script, by 
passing a threshold, it correctly identify the group.

However, when I ask the symmetry operations, it seems to ignore the 
threshold parameters.

I attach an example that works properly with spglib==1.14.1 but not with 
spglib==1.15.1.

The example requires ASE installed to read the ".cif" file. It is a 
slightly displaced C2/c group structure.

If I ask the symmetry group without specifying a threshold, it correctly 
says it is P1 (1), while if I use a small threshold (0.05) it recognizes 
the C2/c (4) group.

Then I ask the code the symmetries and the rotations, by specifying the 
same threshold that allows to recognize the C2/c group, but it returns 
just the identity matrix.

As I told you, if I use an older version of spglib, the code works properly.


Is it a bug? will it be solved in the next release?

Thanks for your attention,

Best regards,

Lorenzo Monacelli