We are a statistical mechanics research group at the University of Minnesota specializing in particle-based computer simulation. Our research efforts are driven by the desire to learn about complex chemical systems on the microscopic, or molecular, level. We focus on understanding how molecular architecture and composition influence structure, phase behavior and function of the system of interest. The challenge of molecular simulation is the ability to make thermodynamic predictions that are both accurate and precise. Accuracy is dependent upon a correct description of molecular interactions in the system, modeled using a force field. Precision is dependent on the degree to which relevant (highly-probable) configurations of the system are sampled. In answering this challenge, our group has developed transferable force fields (TraPPE-UA, TraPPE-EH, TraPPE-pol) that more reasonably model the potential energy of interacting molecules, particularly for the calculation of phase equilibria, and novel simulation algorithms, such as configurational-bias Monte Carlo (CBMC) and aggregation-volume-bias Monte Carlo (AVBMC), for improving the ability to sample important configurations of the system. Our Monte Carlo search algorithms and the Transferable Potentials for Phase Equilibria (TraPPE) force field allow us to predict both accurate and precise thermodynamic data for a wide range of chemical systems, including systems which are not amenable to conventional simulation approaches and for which experimental data are not readily accessible. Please visit our research page to learn more!
Siepmann group graduate student Andrew Sun received a Dissertation Fellowship (DDF). The Doctoral Dissertation Fellowship (DDF) gives the University's most accomplished Ph.D. candidates an opportunity to devote full-time effort to an outstanding research project by providing time to finalize and write a dissertation during the fellowship year.
The award includes a stipend of $25,000 for the academic year (September-May), tuition for up to 14 thesis credits each semester (fall & spring), and subsidized health insurance through the Graduate Assistant Health Plan.
University of Minnesota Twin Cities graduate students and postdoctoral associates, including members of the Siepmann Group, carried out collaborative research on fluid phase and adsorption equilibria that is highlighted on three ACS journal covers in early 2021.
Tao Yang, a graduate student from Xi’an Jiaotong University and visiting scholar at the University of Minnesota, probed the phase equilibria and structure of alternative refrigerant mixtures through experimental measurements and Monte Carlo simulations; the cover illustration depicts a representation of the ternary phase diagram superimposed on the liquid-phase structure. See Yang et al., Ind. Eng. Chem. Res. 2021, 60, 739–752: https://pubs.acs.org/doi/10.1021/acs.iecr.0c05442
Zhengyuan Shen, Qile Chen, and Shuyi Xie, graduate students advised by Lodge and Siepmann, investigated the effects of electrolytes on thermodynamics, structure, and liquid–liquid equilibria of oligo(ethylene oxide) and its blend with squalane in research supported by the University of Minnesota MRSEC; the cover illustration highlights the ion clustering found to be important for these systems. See Shen et al., Macromolecules 2021, 54, 1120–1136: https://pubs.acs.org/doi/10.1021/acs.macromol.0c02270
Collaborative work leading to the development of the Computation Ready Experimental Metal–Organic Framework (CoRE MOF) database by researchers from Pusan National University, University of Minnesota, Northwestern University, IMDEA Materials Institute Madrid, University of Tennessee, Knoxville, Georgia Institute of Technology, University of Nottingham, and University College London supported through the DOE Nanoporous Materials Genome Center is featured on the February 2021 cover of the Journal of Chemical & Engineering Data. The associated research article is Chung et al., J. Chem. Eng. Data 2019, 64, 5985–5998: https://pubs.acs.org/doi/10.1021/acs.jced.9b00835
The artworks for these covers have been designed by Lisa Zeeb and her contributions are deeply appreciated by the authors of the research articles.