Lattice stability and high pressure melting mechanism of dense hydrogen up to 1.5 TPa

Abstract

Lattice stability and metastability, as well as melting, are important features of the physics and chemistry of dense hydrogen. Using ab initio molecular dynamics (AIMD), the classical superheating limit and melting line of metallic hydrogen are investigated up to 1.5 TPa. The computations show that the classical superheating degree is about 100 K, and the classical melting curve becomes flat at a level of 350 K when beyond 500 GPa. This information allows us to estimate the well depth and the potential barriers that must be overcome when the crystal melts. Inclusion of nuclear quantum effects (NQE) using path integral molecular dynamics (PIMD) predicts that both superheating limit and melting temperature are lowered to below room temperature, but the latter never reach absolute zero. Detailed analysis indicates that the melting is thermally activated, rather than driven by pure zero-point motion (ZPM). This argument was further supported by extensive PIMD simulations, demonstrating the stability of Fddd structure against liquefaction at low temperatures.

arXiv comment27 pages, 6 figures, with Supplementary Information (with 16 pages)

References in corpus (15)

• A superconductor to superfluid phase transition in liquid metallic hydrogen
• A quantum fluid of metallic hydrogen suggested by first-principles calculations
• Thermophysical properties of warm dense hydrogen
• Nuclear Quantum Effects and Nonlocal Exchange-Correlation Functionals Applied to Liquid Hydrogen at High Pressure
• Stable liquid Hydrogen at high pressure by a novel ab-initio molecular dynamics
• The Melting Line of Hydrogen at High Pressures
• Quantum simulation of low-temperature metallic liquid hydrogen
• Towards a Predictive First-Principles Description of Solid Molecular Hydrogen with Density-Functional Theory
• Equation of state of metallic hydrogen from Coupled Electron-Ion Monte Carlo simulations
• Higher order and infinite Trotter-number extrapolations in path integral Monte Carlo
• The kinetics of homogeneous melting beyond the limit of superheating
• Room-Temperature Structures of Solid Hydrogen at High Pressures
• Role of Bose Statistics in Crystallization and Quantum Jamming
• High-pressure behavior of dense hydrogen up to 3.5 TPa from density functional theory calculations
• Accelerating ab initio path integral molecular dynamics with multilevel sampling of potential surface

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• Predicted reentrant melting of dense hydrogen at ultra-high pressures
• Optical properties of dense lithium in electride phases by first-principles calculations
• Prediction of a Mobile Solid State in Dense Hydrogen under High Pressures
• Isotope quantum effects in the metallization transition in liquid hydrogen
• Determining the Superconducting Transition Temperatures of Liquids
• Full Temperature-Dependent Potential and Anharmonicity in Metallic Hydrogen: Colossal NQE and the Consequences
• First-principles estimation of the superconducting transition temperature of a metallic hydrogen liquid
• Coexistence of Superconductivity and Superionicity in Li${}_2$MgH${}_{16}$
• Influence of electronic entropy on Hellmann-Feynman forces in ab initio molecular dynamics with large temperature changes
• Prediction of Superionic State in LiH2 at Conditions Enroute to Nuclear Fusion
• Pressure induced Structure Change and Anomalies in Thermodynamic Quantities and Transport Properties in Liquid Lithium Hydride