This grant supports theoretical studies of the light elements, including hydrogen and also the light elements in combination, but placed under conditions of high pressure and also of elevated temperature. The research also includes studies of correlated quantum and classical systems under similar conditions, but with particular emphasis on possible novel states of order. One topic of growing prominence in such systems is the fundamental and increasingly pragmatic area of superconductivity, impelled by the recent and quite dramatic discovery of superconductivity occurring in compressed lithium with a transition temperature of about 20K at 48Gpa, which if substantiated would be the highest of any element. Previous studies had shown that these so-called simple elements could adopt structures of considerable complexity at similar conditions. Further, these elements were observed to take up structures exhibiting incommensurabilities. And it is surely remarkable that the light elements in the straightforward combination MgB2 have such a dramatic effect on the field of superconductivity. %%% These theoretical studies will investigate the electronic properties of the light elements, e.g., hydrogen, lithium, etc., under high pressure and high temperatures. These so-called simple elements yield unexpected rich structures including superconductivity. While the research is very basic, the results will be very beneficial in understanding superconductivity which has many potential applications. The project will support graduate students. ***