Tantalum Equation of State with Uncertainty Quantification using Heterogeneous Data Sources

We apply uncertainty quantification (UQ) techniques to construct an updated SESAME equation of state (EOS) for tantalum by integrating ab initio and experimental data. Using density functional theory (DFT) phonon calculations within the quasi-harmonic approximation, we compute free energy and thermal expansion, incorporating these into the EOS generation framework. Tantalum, with its extensive experimental dataset, serves as a good test case for quantifying uncertainties in high-pressure and high-temperature regimes, where experimental data can be sparse or inconsistent. We also compare different EOS tables generated by subsets of data. By employing Markov Chain Monte Carlo (MCMC) methods, we combine disparate data sources in a coherent framework and quantify uncertainties associated with experimental and computational data.

LA-UR-25-20921