Doctoral Dissertations
Date of Award
8-2022
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Materials Science and Engineering
Major Professor
David J. Keffer
Committee Members
Don M. Nicholson, Haikuan Xu, Orlando Rios
Abstract
Techniques such as classical molecular dynamics [MD] simulation provide ready access to the thermodynamic data of model material systems. However, the calculation of the Helmholtz and Gibbs free energies remains a difficult task due to the tedious nature of extracting accurate values of the excess entropy from MD simulation data. Thermodynamic integration, a common technique for the calculation of entropy requires numerous simulations across a range of temperatures. Alternative approaches to the direct calculation of entropy based on functionals of pair correlation functions [PCF] have been developed over the years. This work builds upon the functional approach tradition by extending the recently developed entropy pair functional theory [EPFT] to three new material systems. Direct calculations of entropy for the BCC iron and FCC copper (modeled with the modified embedded atom method [MEAM] potential) and the Diamond Cubic silicon system (modeled with the Tersoff potential) are compared against a target entropy as determined by thermodynamic integration. The sources of and correction to the high temperature error in several proposed functional approaches is explored in depth. Finally, a working code is provided to the community via Github to implement the extended EFPT to compute entropy using trajectory files generated from a single simulation.
Recommended Citation
Sluss, Clifton C., "Direct Calculation of Configurational Entropy: Pair Correlation Functions and Disorder. " PhD diss., University of Tennessee, 2022.
https://trace.tennessee.edu/utk_graddiss/7242
Included in
Computational Engineering Commons, Numerical Analysis and Scientific Computing Commons, Other Materials Science and Engineering Commons, Statistical, Nonlinear, and Soft Matter Physics Commons