Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures

Drummond, Neil D. and Monserrat, Bartomeu and Lloyd-Williams, Jonathan H. and Rios, P. Lopez and Pickard, Chris J. and Needs, R. J. (2015) Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures. Nature Communications, 6. ISSN 2041-1723

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Abstract

Establishing the phase diagram of hydrogen is a major challenge for experimental and theoretical physics. Experiment alone cannot establish the atomic structure of solid hydrogen at high pressure, because hydrogen scatters X-rays only weakly. Instead, our understanding of the atomic structure is largely based on density functional theory (DFT). By comparing Raman spectra for low-energy structures found in DFT searches with experimental spectra, candidate atomic structures have been identified for each experimentally observed phase. Unfortunately, DFT predicts a metallic structure to be energetically favoured at a broad range of pressures up to 400[thinsp]GPa, where it is known experimentally that hydrogen is non-metallic. Here we show that more advanced theoretical methods (diffusion quantum Monte Carlo calculations) find the metallic structure to be uncompetitive, and predict a phase diagram in reasonable agreement with experiment. This greatly strengthens the claim that the candidate atomic structures accurately model the experimentally observed phases.

Item Type:
Journal Article
Journal or Publication Title:
Nature Communications
Additional Information:
Supplementary information available for this article at http://www.nature.com/ncomms/2015/150728/ncomms8794/suppinfo/ncomms8794S1.html
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
ID Code:
75208
Deposited By:
Deposited On:
12 Aug 2015 13:38
Refereed?:
Yes
Published?:
Published
Last Modified:
02 Jun 2020 02:48