2020/07/07 by Francisca Sagredo, Kieron Burke, Sagredo, Francisca +1 · 1 citation
Engineering · Physics and Astronomy · #Advanced Chemical Physics Studies #Advanced Thermodynamics and Statistical Mechanics #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Phase Equilibria and Thermodynamics #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2007.03840
openalex publication_date 2020/07/07 · openalex created_date 2022/07/26 · openalex updated_date 2026/07/28
The landmark 1982 paper of Perdew, Parr, Levy, and Balduz (often called PPLB)\nlaid the foundation for our modern understanding of the role of the derivative\ndiscontinuity in density functional theory, which drives much development to\naccount for its effects. A simple model for the chemical potential at vanishing\ntemperature played a crucial role in their argument. We investigate the\nvalidity of this model in the simplest non-trivial system to which it can be\napplied and which can be easily solved exactly, the Hubbard dimer. We find\nexact agreement in the crucial zero-temperature limit, and show the model\nremains accurate for a significant range of temperatures. We identify how this\nrange depends on the strength of correlations. We extend the model to\napproximate free energies accounting for the derivative discontinuity, a\nfeature missing in standard semi-local approximations. We provide a correction\nto this approximation to yield even more accurate free energies. We discuss the\nrelevance of these results for warm dense matter.\n