Dr. Beratan is developing theoretical approaches to understand the function of complex molecular and macromolecular systems, including: the molecular underpinnings of energy harvesting and charge transport in biology; the mechanism of solar energy capture and conversion in man-made structures; the nature of charge conductivity in naturally occurring nucleic acids and in synthetic constructs, including the photochemical repair of damaged DNA in extremophiles; CH bond activation by copper oxygenase enzymes; the flow of charge in bacterial appendages on the micrometer length scale; the theoretical foundations for inverse molecular design - the property driven discovery of chemical structures with optimal properties; the exploitation of molecular diversity in the mapping of molecular and materials "space"; the use of infra-red excitation to manipulate electron transport through molecules; the optical signatures of molecular chirality and the influence of chirality on charge transport.