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arXiv · 1001.2079

Fundamental high pressure calibration from all-electron quantum Monte Carlo calculations

K. P. Esler·R. E. Cohen·B. Militzer·Jeongnim Kim·R. J. Needs·M. D. Towler
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Abstract

We develop an all-electron quantum Monte Carlo (QMC) method for solids that does not rely on pseudopotentials, and use it to construct a primary ultra-high pressure calibration based the equation of state of cubic boron nitride(c-BN). We compute the static contribution to the free energy with QMC, and obtain the phonon contribution from density functional theory, yielding a high-accuracy calibration up to 900 GPa usable directly in experiment. Furthermore, we compute the anharmonic Raman frequency shift with QMC as a function of pressure and temperature, allowing optical pressure calibration in table-top experiments. In contrast to present experimental approaches, small systematic errors in the theoretical EOS do not increase with pressure, and no extrapolation is needed. This all-electron methodology is generally applicable to first-row solids, and can be used to provide a new reference for ab initio calculations of solids and to benchmark pseudopotential accuracy.

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K. P. Esler, R. E. Cohen, B. Militzer, Jeongnim Kim, R. J. Needs, M. D. Towler. 2010-01-13. Fundamental high pressure calibration from all-electron quantum Monte Carlo calculations. https://doi.org/10.1103/physrevlett.104.185702

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