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Center for Nonlinear Studies |
As the world’s population grows and further industrializes, its energy demands also increase. This increase in energy consumption introduces the need to not only to develop renewable energy sources, but to also find ways of making current sources less detrimental to the environment. Nanoscale systems such as quantum dots and metal organic frameworks exhibit many properties that, if harnessed properly, could greatly improve development of applications ranging from solar cells, photovoltaic devices, gas storage and gas separation. Theoretical methods that are able to accurately simulate the real-time evolution of excited state dynamics in nanoscale systems are necessary for application development. Nonadabatic molecular dynamics with fewest switches surface hopping within an ab initio density functional theory framework has been implemented in commercial, open source, and in-house codes to model the real-time dynamics of excited state evolution in systems consisting of up to hundreds of atoms.
Recently, we used a local orbital code called FIREBALL to study the photoisomerization process in azobenzene derivatives. Azobenzene functional groups undergo photoisomerization upon light irradiation or application of heat. Zhou et al. (J. Am. Chem. Soc. 134, 99-102, 2012) showed that these azobenzenes can then be introduced into metal-organic frameworks (MOF) via an organic linker in order to create a reversible switch for CO2 adsorption. Preliminary results indicate that the optical properties, reaction time, and quantum yield depend on the azobenzene derivative being used. We apply nonadiabatic molecular dynamics to the azobenzene derivatives in order to better theoretical understanding of the trans- to cis- transformation mechanism, and timescale variations that result from different functional groups. The long term goal is to use high throughput calculations for rational system design.
Host: Sergei Tretiak