## Research Abstracts Online

January 2009 - March 2010

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### University of Minnesota Duluth

Swenson College of Science and Engineering

Department
of Chemistry and Biochemistry

# PI: Paul D. Siders

### Entropy Production in a Drive Lattice Gas

The goal of this project is to calculate the rate of entropy production in simple nonequilibrium lattice models, to test the hypothesis that steady states of driven systems maximize the rate of entropy production. Models under study are simple enough that entropy production can be calculated accurately and transparently. Two types of external driving force will be used: mechanical drive (e.g., particle flow under gravity) and chemical potential (reactions coupled to reagent reservoir and product sink). In the first type of model, a mechanical drive is applied to lattice-gas particles on square, hexagonal and triangular two-dimensional lattices. The driving force induces steady-state particle current, which is proportional to entropy production. During the past research period, calculations at MSI characterized driven gases by molecular dynamics. Calculations will now shift to master-equation solutions for lattices small enough to allow near-exact calculation of current, but large enough to allow a nonequilibrium phase transition, will be used. In the second type of system, entropy production of chemical reaction mechanisms that permit oscillation will be studied. Specifically, reversible bimolecular versions of the Brusselator, Wilhelmâ€™s minimal oscillator, and the Willamowski-Rossler oscillator will be driven by spatial concentration gradients. Entropy production of the resulting oscillating or steady states will be calculated.

### Group Members

Sara Ford, Undergraduate Student

Carl Sandness, Faculty, Hibbing High School, Hibbing, Minnesota

Jeffrey Weilage, Undergraduate Student

Kelsey C. Zielke, Undergraduate Student