Improvement of anisotropic displacement parameters from invariom-model refinements for three L-hydroxylysine structures

Three L-hydroxylysine structures have been determined at 100 K by single-crystal X-ray diffraction. High-resolution data using either a laboratory or synchrotron source were collected and subjected to invariom-and independent atom-model (IAM) refinements. Anisotropic displacement parameters (ADPs) obtained from invariom refinement were compared (i) with results from a full multipole and (ii) with an IAM high-order refinement. Differences were visualized with the program PEANUT and were complemented by quantitative results from a Hirshfeld test. Influences of scale factor differences, and of refinement against F-2 versus F, have been investigated. Systematic errors were observed in the IAM, especially when only low-order data were available. Although these errors were reduced in high-order IAM refinements, they only disappeared in charge density - and likewise invariom refinements.