Hi Hari,

1) I was wondering if someone can point me to routines available from cctbx modules that can give me the "resolution" for a given index "h" "k" "l". in any space group

To get the resolution for a given hkl, you just need the unit cell: from cctbx import uctbx uc = uctbx.unit_cell((11,12,13,93,98,103)) hkl = (2,3,4) print uc.d(miller_index=hkl) print uc.stol(miller_index=hkl) wavelength = 1.3 print uc.two_theta(miller_index=hkl, wavelength=wavelength) Save as "resolution_hkl.py" and run with: cctbx.python resolution_hkl.py The .d(), .stol(), .two_theta() methods are documented here: http://cctbx.sourceforge.net/current/c_plus_plus/classcctbx_1_1uctbx_1_1unit...

2) In addition , if someone can point me in the direction of a well illustrated depiction of the derivation of the reciprocal lattice for the triclinic case , that will be very much appreciated bonus .

I'm not sure which textbook to recommend. I liked the old Buerger books a lot, but I don't remember how he introduces the reciprocal lattice. Ralf