W0420

Structural Analysis of Modulated Structures. ¹Siegbert Schmid & ²Trixie Wagner, ¹School of Chemistry, The Univ. of Sydney, NSW 2006, Australia, (siegbert@chem.usyd.edu.au); ²Novartis, Basel, Switzerland.

Systems that form modulated structures are a fascinating class of materials that lack conventional lattice periodicity but are still perfectly long-range ordered. Such systems exist across the whole range of chemical disciplines from organic conductors and minerals to ceramic materials like high-T_c superconductors and ferroelectrics.

Modulated structures (commensurate or incommensurate) are characterised by a distinct hierarchical intensity distribution in reciprocal space (see Figure 1). This talk will investigate some of the basic features of modulated structures. In particular we will examine the types of modulated structures, how to recognise them and what to do about data collection, structure solution and refinement strategies. This introductory presentation will be aimed at scientists that have limited or no experience with modulated structures.