Import wizard defaults to lowest point group in laue class, rounds unit cell parameters (at least for .ang?)

[Tom-G-Uni-Vienna]

Hi all,

Expert users probably don't use the import wizard function much any more, however it comes up a lot in teaching and self-learning.

In modern MTEX versions (including 5.11.1), when the import wizard is used to import a .ang file (at least, the .ang files I have available to me, from OIM Analysis version 8.0), the automatically suggested Point Group for crystalline phases is not the actual point group of the phase, but instead the lowest symmetry point group for that Laue Class (the one that is rotations only, e.g. 432 for a cubic phase).

Possibly this is as designed, but if so, I missed why! For me it would make sense for the default to be the actual point group. Often when I am helping people just getting into MTEX, I see that they have the incorrect point groups in their crystal symmetries as they did not realise that MTEX was not reading the actual point group listed in the file. I think that even if there is a reason to choose a lower symmetry point group, this should be an active choice by the user, not a default.

A related issue is that in the .m file generated by the wizard for the import script, the unit cell lengths are always rounded to just 2 significant figures, regardless of the unit cell parameter precision in the .ang file, and although the unrounded parameters are shown in the import wizard window itself (typically to 4.s.f).

Unfortunately, I have no way of knowing if this issue is specific to just .ang files, or even, specific to just .ang files generated by certain OIM analysis versions. For me, the issue occurs with all .ang files I have available.

best regards,
Tom G