Structure and bandgap closure in dense hydrogen

Article Abstract:

It appears that the paired state of hydrogen is tenacious at high pressures. A metallic pairing state could precede eventual pair dissociation. This research has extended theoretical work designed to determine the optimal crystal structure with techniques including quantum Monte Carlo methods. It was possible to make density functional calculations within the local density approximation that predict a range of densities for hydrogen where a paired or molecular metallic state could be energetically preferred. The possibility of a paired band-overlap state is of some experimental interest.

Hydrogen bonding, Hydrogen bonds

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Spontaneous polarization in dense hydrogen

Article Abstract:

Mathematical calculations of the structure of solid hydrogen subjected to the highest pressures yet reached will likely explain why the attempt to transform solid hydrogen to a dense, low-temperature metallic state has continued to elude researchers. The calculations are based on electronic density-functional theory. They show that when solid hydrogen is subjected to ultra-high pressure, its structure develops a spontaneous polarization such that the intermolecular vibrational mode or vibron becomes infrared-active, which might result in a delayed transition to a metallic state.

Hydrogen

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Emergent reduction of electronic state dimensionality in dense ordered Li-Be alloys

Article Abstract:

The impact of high pressure on the reactivity and electronic state of the dense ordered Li-Be alloys is discussed. The finding shows that the electronic state dimensionality of such alloys reduce with the density.

Science & research, Observations, Chemical properties, Lithium alloys, Ionospheric electron density

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