Delta-amplitudes calculation input

Since the input files for the delta calculations are highly redundant (one “delta calculation” is performed for each separate delta file), input is collected in the delta-input file. The input files listed are of two different categories:

• PARAM files: Define static fortran array sizes. Every different instance of PARAM requires re-compiling the delta calculation fortran code, so delta input is grouped by files that can run based on the same PARAM files. In the delta-input code, PARAM is printed whenever it changes, and then proceeded by all input files that can use this PARAM.

• Input for specific delta calculations: Contains the energy range to calculate (from THEO_ENERGIES), the surface and bulk unit cell vectors (from POSCAR and SUPERLATTICE), and the BEAM_INCIDENCE. Then contains the entire content of the AUXBEAMS and PHASESHIFTS files, which are abbreviated simply as [AUXBEAMS] and [PHASESHIFTS] in the delta-input file. Then assigns an index of blocks in the PHASESHIFTS file to use, and lists all geometrical and vibrational displacements, as given in the DISPLACEMENTS file.