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Running Statistical Mechanics "In Reverse": Converting High-Temperature Measurements into 0 Kelvin Predictions

Thursday (29.09.2016)
11:15 - 11:30
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Effective Hamiltonians in tandem with statistical mechanics offer a rigorous connection between 0 Kelvin ab-initio simulations and finite temperature experimental observations. Specifically, cluster expansion Hamiltonians can extrapolate the complex, many-body electron problem of density functional theory (DFT) into a series of products-of-sites on an atomic scale. The resulting energy polynomial is computationally inexpensive, and hence suitable for the (tens of) thousands of calculations of thousand-site systems required by stochastic methods. We present a new method to run a cluster expansion "in reverse", taking high-temperature observations and using thermodynamic connections to predict the 0 Kelvin energy spectrum and associated ground states. By re-examining the cluster expansion formalism through the lens of entropy-maximization approaches, we develop an algorithm to select clusters and determine cluster interactions using only a few, high-temperature experiments on disordered phases. We will demonstrate our new approach, and also describe two systems we have studied using traditional DFT-backed cluster expansions: the Co-Pt binary alloy, and the MnRu2Sn-FeRu2Sn pseudo-binary.

Elizabeth Decolvenaere
University of California: Santa Barbara
Additional Authors:
  • Prof. Michael Gordon
    University of California: Santa Barbara
  • Prof. Anton Van der Ven
    University of California: Santa Barbara