Since hydrogen atoms were historically assumed to be too small to scatter X-rays, they’re allowed to “ride” on larger atoms during this computational step. For 10 points each:
[10m] Name this final step of solving a crystal structure in which software like SHELX fine-tunes a model’s bond angles and lengths to fit experimental data and physical constraints.
ANSWER: structure refinement [or relaxation; accept refining or relaxing]
[10h] In 1977, this chemist proclaimed that hydrogens could never be resolved by XRD; thus, when Jayatilaka et. al. finally figured out how to refine hydrogen atoms in 2014, they named the technique for him. This Weizmann Institute chemist also names a method of partitioning electron density.
ANSWER: Fred (F.L.) Hirshfeld [accept Hirshfeld atom refinement or Hirshfeld partition]
[10e] Hirshfeld atom refinement works by assuming the atoms do not have this symmetrical shape. This is the shape of an s orbital.
ANSWER: sphere [or spherical]
<S, Chemistry>