Electronic Excited States of Biomolecular Systems: Ab Initio FSGO-based Quantum Mechanical Methods with Applications to Photosynthetic and Related Systems

The accelerating rate with which new computer hardware is being introduced has spurred development of a wide variety of sophisticated scientific software for the simulation of chemical and biological systems. Molecular mechanics and dynamics methods, which are based on potential energy functions derived from empirical and quantum mechanically calculated data, are now widely employed in investigations of the conformations and interactions of molecules in their ground electronic states. Applications to systems as complex as proteins and nucleic acids have made significant contributions to our understanding, especially as regards the molecular basis of structure and function. Direct application of quantum mechanical methods to such studies of large biomolecules have been sparse, and have not, in general had the impact that molecular mechanical and dynamical methods have had in shaping our understanding of these systems. When dealing with electronic excited states, however, quantum mechanical methods are required. And knowledge of the electronic structure and properties of these states is important for a detailed understanding of a number of photobiological processes (such as photosynthesis and vision), and for analyzing and interpreting the results obtained from applications of absorption, emission, and circular dichroism spectroscopy to the study of individual and interacting biomolecules.