Produce a .ins (instrument) input file for SHELX

[RichardWaiteSTFC]

Is your feature request related to a problem? Please describe. SHELX requires a .ins file as input fro single-crystal refinements (possibly also powder) - currently mantid does not produce this Reported by Nick Funnell

Describe the solution you'd like Mantid would produce a .ins file

Describe alternatives you've considered Currently hand-made by each user - quite a lengthy process.

Additional context The specification for a .ins file are as follows from top line to bottom of attached file roy40_3d.txt:

• A title line
• A comment line (denoted by ‘REM’)
• CELL - Cell dimensions with a dummy wavelength value (0.7) for whitebeam
• ZERR - Number of formula units in the cell ‘Z’ (=4) and the errors ‘ERR’ on the cell dimensions
• LATT instruction – a number code for the centring. 1 = P, 2 = I, 3 = R, etc. A negative value indicates non-centrosymmetric
• SYMM – symmetry operators for space group number 14 P21/n. You’ll see more operations defined in the international tables (4 of them) but one line is all you need here; ‘x, y, z’ is assumed. Then if you combine these two operations with the inversion symmetry indicated by the LATT instruction, then you can generate all 4 SYMM positions.
• NEUT – this is neutron data
• SFAC – this specifies the scattering factors for each atom type, with values corresponding to neutrons. I’m not 100% sure if this detail is still required because I think the NEUT instruction should deal with this. It could be a hangover of earlier versions of the program. Silvia will know better than me.
• UNIT – number of each atom type in the unit cell
• MERG 0 – instruction not to merge the data (otherwise default is to merge symmetry-equivalent reflections)
• HKLF2 - .hkl file format 2
• END

Documentation: https://cpb-us-w2.wpmucdn.com/web.sas.upenn.edu/dist/f/266/files/2016/11/shelxl_comlist-1mp04in.pdf