Evaluation of exchange-correlation functionals with multiple-shock conductivity measurements in hydrogen and deuterium at the molecular-to-atomic transition
- Washington State Univ., Pullman, WA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of Rostock, Rostock (Germany)
The temperature (T) and density (ρ) conditions at which hydrogen undergoes a molecular-to-atomic (MA) transition is crucial to our understanding of the gas-giant planets such as Jupiter and Saturn. First-principles (FP) calculations suggest that this transition is coincident with metallization and acts as a catalyst for hydrogen-helium demixing, which has significant consequences for models of planetary interiors. Prediction of this transition boundary has proven to be difficult using FP methods. In particular, detailed comparisons of finite temperature density functional theory (FT-DFT) calculations of the MA transition in both the high-T, low-ρ regime, where the transition is largely T driven, and the low-T, high-ρ regime, where the transition is largely ρ driven, suggest that the transition is very sensitive to the exchange-correlation (xc) functional used in the calculation. Here we present a detailed comparison of previous multiple-shock electrical conductivity measurements with FT-DFT calculations employing various xc functionals to probe a regime where both T and ρ play an important role in the transition. The measurement results are found to be inconsistent with the semilocal xc functional PBE and are in much better agreement with the nonlocal xc functionals vdW-DF1 and vdW-DF2. Furthermore, we show that the inconsistency with PBE likely stems from pressure errors associated with the PBE xc functional, resulting in calculated pressures that are too low at these T and ρ conditions. Together with previous comparisons at high-T, low-ρ and low-T, high-ρ these results provide a consistent picture for the MA transition over a wide T and ρ range. Here, this picture may also provide insight into differences in experimental observations of the metallization of liquid hydrogen and deuterium in the low-T regime.
- Research Organization:
- Washington State Univ., Pullman, WA (United States). Inst. for Shock Physics
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP)
- Grant/Contract Number:
- NA0002007; NA0003525
- OSTI ID:
- 1493764
- Alternate ID(s):
- OSTI ID: 1492145
- Journal Information:
- Physical Review B, Vol. 98, Issue 17; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Metastable molecular fluid hydrogen at high pressures
|
journal | April 2019 |
Plasma phase transition (by the fiftieth anniversary of the prediction)
|
journal | March 2019 |
Benchmarking vdW-DF first-principles predictions against Coupled Electron-Ion Monte Carlo for high-pressure liquid hydrogen
|
journal | February 2019 |
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