9217464 Kirtman This U.S.-Brazil Cooperative Science award will support the collaboration of Bernard Kirtman of the University of California at Santa Barbara and Celso de Melo of the Federal University of Pernambuco, Brazil. The project aims to investigate the nonlinear optical properties of conjugated polymers. The researchers will formulate theoretical methods that permit an accurate, comprehensive description of these properties, which include distortion due to coupling of vibrations with electronic polarization induced by the oscillatory incident field(s); electron correlation; and non-resonant frequency dispersion. Ab initio quantum chemistry calculations of all three effects will be done for the prototype pi-conjugated polymer, trans- polyacetylene using the finite oligomer approach. A transfer matrix method for circumventing the extrapolations required with this procedure will also be investigated. Both the U.S. and Brazilian sides will gain an understanding of the interaction between high intensity optical radiation and conjugated polymers, which could potentially improve the design of polymeric materials for practical purposes. Students and postdocs on both sides will benefit from training in non-conventional polymer methodologies. ***
