Premium
Aspherical scattering factors for SHELXL – model, implementation and application
Author(s) -
Lübben Jens,
Wandtke Claudia M.,
Hübschle Christian B.,
Ruf Michael,
Sheldrick George M.,
Dittrich Birger
Publication year - 2019
Publication title -
acta crystallographica section a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.742
H-Index - 83
ISSN - 2053-2733
DOI - 10.1107/s2053273318013840
Subject(s) - formalism (music) , computation , gaussian , quantum chemical , electron density , scattering , density functional theory , statistical physics , algorithm , computational chemistry , computer science , physics , materials science , quantum mechanics , chemistry , electron , molecule , art , musical , visual arts
A new aspherical scattering factor formalism has been implemented in the crystallographic least‐squares refinement program SHELXL . The formalism relies on Gaussian functions and can optionally complement the independent atom model to take into account the deformation of electron‐density distribution due to chemical bonding and lone pairs. Asphericity contributions were derived from the electron density obtained from quantum‐chemical density functional theory computations of suitable model compounds that contain particular chemical environments, as defined by the invariom formalism. Thanks to a new algorithm, invariom assignment for refinement in SHELXL is automated. A suitable parameterization for each chemical environment within the new model was achieved by metaheuristics. Figures of merit, precision and accuracy of crystallographic least‐squares refinements improve significantly upon using the new model.