Inclusion of spglib support for symmetrization
An interface to the spglib library is now quite mature and almost ready to be merged. This issue is a placeholder to organize the steps to be taken, including addressing some issues before a proper merge request.
Main code changes:
Interface to spglib:
Module with siesta objects which then calls spglib:
m_syms.F90. It is enough to use this module in order to access the objects symops etc...
The symmetry init routine is called from
Src/siesta_init.F, which also outputs basic information (too verbose for the moment)
One can currently enforce symmetries on:
- structure - Src/siesta_init.F
- Forces - Src/state_analysis.F
Options for input file:
- ../Src/read_options.F90: impose_symmetries = fdf_get ('ImposeSymmetries', .true.)
- ../Src/read_options.F90: syms_prec = fdf_get ('ToleranceSymmetries', 1.d-6)
Rapidly implementable other uses for the symmetries:
- k-point grid reduction (implies completing the density matrix, maybe states as well, using symmetries)
- reduction of perturbations in DFPT (idem). To be discussed with Miguel eventually
- things for images and constraints that Arsalan wanted to do, with NEB or other algorithms acting on instances with different space groups.
The code is currently in this branch