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Gas Giants: Jupiter and Saturn
Published in Thomas Hockey, Jennifer Lynn Bartlett, Daniel C. Boice, Solar System, 2021
Thomas Hockey, Jennifer Lynn Bartlett, Daniel C. Boice
The pressure increases even more such that, at a radius 80–90% of the planet and a pressure three million times that at the Earth's surface, Jupiter is squeezed so tightly that electricity can easily flow through the hydrogen. It becomes a very good conductor. Because it has the properties associated with metals, chemists call this strange kind of hydrogen: metallic hydrogen. Nobody has even seen an ocean of metallic hydrogen. However, laboratory experiments show that hydrogen must become metallic under these extreme conditions.
Electronic structure, thermodynamic properties and metallic behaviours of hydrogen
Published in Molecular Physics, 2021
Mahdi Kheirmand, Neda Heydari, Seyed Mohammad Azami
Electrical conductivity, one of the most important properties for metals, is still not completely clear for metallic hydrogen. One of the theoretical investigations of electroresistivity of metallic hydrogen is electron–proton interaction within the framework of perturbation theory, where Shvets et al. have employed Kubo linear response theory using the two-time retarded Green functions method to calculated the relaxation time [12]. They understood that the second-order contribution to electoresistivity is of the same order as for majority of the liquid metals that were well described using the nearly free electrons approximation. Some scientists like Ashcroft, based on expected strong coupling between conduction electrons and lattice vibrations, suggested that metallic hydrogen might be a superconductor [13]. Bardeen–Cooper–Schrieffer (BCS) theory is the first theory for superconductivity that Ashcraft in 1968 used for metallic hydrogen in which the Deby temperature was estimated to be 3.5 × 103 K and predicted that if metallic hydrogen exists in a close-packed phase (e.g. hcp or fcc) the screened point-ion potential is large enough for significant zone contact with the Fermi surface [13]. Continuing this hypothesis, Barbee et al., presented the first ab-initio calculation in a distorted hexagonal high pressure (400 GPa) phase of hydrogen using standard BCS-Eliashberge and estimated the superconducting phase transition temperature to be 230 ± 85 K [14]. Some other researchers also used BCS-like theory to estimate the properties of metallic hydrogen in hydrogen-rich structures, such as silane [15]. Another method for estimation of electrical conductivity is to investigate energy levels and HOMO–LUMO gap. Chacham and Louie performed quasiparticle calculations for the HOMO–LUMO gap of solid molecular hydrogen in the hcp structure [16] and found out that the HOMO–LUMO gap ranges from 14.5 to 0.03 eV from low pressure to 300 GPa.