Tools for Accurate Photoelectrochemistry in Complex Environments

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Troy Van Voorhis of the Massachusetts Institute of Technology is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to develop theoretical methods and tools to reveal how complex chemical transformations can better be accomplished using renewable energy sources such as sunlight and electricity derived from sustainable sources. The microscopic structure of such systems is very complex and the nature of structure-function relationships in these devices is as yet not well understood. Simulation and modeling play a crucial role in uncovering design principles that can be exploited to optimize device performance or to propose entirely new architectures for specific applications. The techniques developed in the course of this research will be applicable to molecules that play key functional roles in many important technological applications such as artificial photosynthesis, organic LEDs, catalysis and chemical sensing. In terms of broader impact, the investigators are actively involved in expanding the base of chemistry-related problem types that can be offered through the edX platform. Under this award, the Van Voorhis research group plans to develop and implement computational tools that that focus on extending the techniques of ground state electronic structure theory to the accurate treatment of electronic excited states. In order to improve the description of electronic excited states, the investigators will design electronic embedding schemes that offer controllable accuracy for the local electronic structure even of highly delocalized systems. These methods are to be complemented with a set of nonlocal density functional tools for including long-ranged interactions such as screening. Contemporary with this electronic structure work, the team seeks to develop molecular dynamics techniques capable of extracting long time kinetic data from short time ab initio simulations. These techniques are designed to understand two key electronic processes: charge carrier delocalization in conjugated polymers and the band gaps of inorganic semiconductors. Beyond these case studies, the work also aims to create a palette of general techniques for the accurate description of photochemistry in solution and electrochemistry at surfaces.