Restrained refinement and results analysis for incommensurate crystal structures

Restraint equations suitable for incommensurate (IC) structure refinement by least squares are defined. Other quantities used in the final results analysis are reviewed. The main purpose of such a restrained refinement is to prevent high local variations of stereochemical parameters (e.g. bond lengths and/or angles), leaving the corresponding average values to be refined. The method is a natural generalization of that commonly used for commensurate structures and in some cases does not require user-supplied parameters.