Striking Isotope Effect on the Metallization Phase Lines of Liquid Hydrogen and Deuterium

Abstract

Liquid atomic metallic hydrogen is the simplest, lightest, and most abundant of all liquid metals. The role of nucleon motions or ion dynamics has been somewhat ignored in relation to the dissociative insulator-metal transition. Almost all previous experimental high-pressure studies have treated the fluid isotopes, hydrogen and deuterium, with no distinction. Studying both hydrogen and deuterium at the same density, most crucially at the phase transition line, can experimentally reveal the importance of ion dynamics. We use static compression to study the optical properties of dense deuterium in the pressure region of 1.2-1.7 Mbar and measured temperatures up to ~3000 K. We observe an abrupt increase in reflectance, consistent with dissociation-induced metallization, at the transition. Here we show that at the same pressure (density) for the two isotopes, the phase line of this transition reveals a prominent isotopic shift, ~700 K. This shift is lower than the isotopic difference in the free-molecule dissociation energies, but it is still large considering the high density of the liquid and the complex many-body effects. Our work reveals the importance of quantum nuclear effects in describing the metallization transition and conduction properties in dense hydrogen systems at conditions of giant planetary interiors, and provides an invaluable benchmark for ab-initio calculations.

arXiv comment12 pages with 3 figures plus Supplementary Information (14 pages and 7 figures)

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Cited by in corpus (14)

• First principles simulations of dense hydrogen
• Thermodynamic anomalies and three distinct liquid-liquid transitions in warm dense liquid hydrogen
• Optical properties of high pressure liquid hydrogen across molecular dissociation
• Fully Consistent Density Functional Theory Determination of the Insulator-Metal Transition Boundary in Warm Dense Hydrogen
• Towards the same line of liquid-liquid phase transition of dense hydrogen from various theoretical predictions
• Electronic energy gap closure and metal-insulator transition in dense liquid hydrogen
• Isotope quantum effects in the metallization transition in liquid hydrogen
• Finite element simulation of the liquid-liquid transition to metallic hydrogen
• Breakdown of Fermi degeneracy in the simplest liquid metal
• Non-adiabatic effects and exciton-like states during insulator-to-metal transition in warm dense hydrogen
• Hydrogen liquid-liquid transition from first principles and machine learning
• Insulator-metal transition in liquid hydrogen and deuterium
• A Denser Hydrogen Inferred from First-Principles Simulations Challenges Jupiter's Interior Models
• Organic compounds in metallic hydrogen