Fiscal Year 2007

The goal of this project is to apply powerful new simulation techniques to tackle computationally challenging problems in chemical dynamics, with special emphasis on electrochemistry, heterogeneous catalysis, nanoparticles, solid-state dynamics, and photochemistry. These calculations will be carried out with new high-throughput integrated software that we are developing. New research capabilities in computational chemical dynamics are expected to play a significant role in enabling environmental scientists worldwide to address environmental challenges facing DOE and the nation. Recent advances in computer power and algorithms have made possible accurate calculations of many chemical properties for both equilibria and kinetics. Nonetheless, applications to complex chemical systems, such as reactive processes in the condensed phase, remain problematic due to the lack of a seamless integration of computational methods that allow modern quantum electronic structure calculations to be combined with state-of-theart methods for chemical thermodynamics and reactive dynamics. These problems are often exacerbated by unvalidated methods and limited software reliability. Our consortium is developing an integrated software suite that combines electronic structure packages with dynamics codes and efficient sampling algorithms for the following kinds of condensed-phase modeling problems that we propose to tackle in various parts of the present Grand Challenge project: thermochemical kinetics and rate constants, photochemistry and spectroscopy, chemical and phase equilibria, electrochemistry, and heterogeneous catalysis. These fundamental areas of research are important for solar energy, fuel-cell technology, environmental remediation, weather modeling, pollution modeling, and atmospheric chemistry. Photochemical creation of excited states offers a means to control chemical transformations because different wavelengths of light can be used to create different vibronic states, thereby directing chemical reactions along different pathways. It is crucial to understand how energy deposited into the system is used; this is particularly complicated in condensed phase systems where there are many ways to dissipate excess energy. Similar opportunities and challenges present themselves in the areas of electrochemistry and catalysis. We therefore propose to carry out prototype large-scale applications on environmental problems as well as other applications to complex chemical dynamics processes, focusing on three high-impact areas. In the computational electrochemistry area, we will be especially concerned with processes that enhance the design of fuel cell technology. For heterogeneous, nanoparticle, and solid-state dynamics, we will develop an array of methods for multi-time-scale simulation of nucleation of crystals in solution, reactions of radicals in solution, zeolite catalysis, structure and dynamics of gallazane precursors to gallium nitride nanocrystals, the regulatory role of metal ions in the reactivity of inorganic phosphates, nanoparticles structure, and ice dynamics. In the computational photochemistry area, we will construct potential energy surfaces for a number of photochemical reactions and employ them for dynamics calculations based on the new decay of mixing with coherent switches algorithm. If time permits, we will also consider solvatochromic shifts on conical intersections that govern selected photo chemical processes.