Volume 3 Issue 7, July 2007
In the laboratory, under the highest currently attainable pressure, hydrogen solidifies but remains insulating even though theoretical calculations suggest it should be metallic (and perhaps superconducting). Higher-pressure studies will settle this question. In the meantime. the actual atomic structures of the highpressure phases of hydrogen are the subject of debate. Part of the problem is the paucity of experimental data to constrain theoretical calculations, for which huge tracts of phase space must be searched for possible structures. To reduce the effort, Chris Pickard and Richard Needs have come up with a computational approach that optimizes the enthalpy as a function of the atomic configuration. Their candidate structure for phase III hydrogen is not only stable and insulating but agrees with available experimental evidence, thus revising the phase diagram of the simplest element.
Editorial
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