id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,workpackage 1156,dnn should be lattice spacing for paracrystalline models,pkienzle,butler,"[Copied from ticket comment:4:ticket:805] The parameter to the model is labelled as nearest neighbour distance, but I believe it is lattice spacing. In units of lattice spacing, a, the q positions of the peaks are well determined by: q = 2*pi/a * sqrt(h^2 + k^2 + l^2) where SC allows all integer hkl, BCC requires h+k+l even and FCC require hkl all even or hkl all odd. Also need peak multiplicity to predict the peak height, since {{{[100] = [-100] = [010] = [0-10] = [001] = [00-1]}}}, etc. I checked peak position and height for dnn=20 and d_factor=0.06 for sc, bcc and fcc to verify the calculation. We should rename dnn to length_a as in the parallelepiped model, and rename d_factor to lattice_distortion. Lattice distortion is actually proportional, Delta a / a, but distortion_proportion is too much of a mouthful.",defect,assigned,critical,SasView 4.3.0,SasView,,,,SasView Bug Fixing