First-Principles Prediction of the Softening of the Silicon Shock Hugoniot Curve
| Autor: | Hu, S. X., Militzer, B., Collins, L. A., Driver, K. P., Kress, J. D. |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Physical Review B, 2016 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.94.094109 |
| Popis: | Shock compression of silicon (Si) under extremely high pressures (>100 Mbar) was investigated by using two first-principles methods of orbital-free molecular dynamics (OFMD) and path integral Monte Carlo (PIMC). While pressures from the two methods agree very well, PIMC predicts a second compression maximum because of 1s electron ionization that is absent in OFMD calculations since Thomas-Fermi-based theories lack shell structure. The Kohn-Sham density functional theory is used to calculate the equation of state (EOS) of warm dense silicon for low-pressure loadings (P < 100 Mbar). Combining these first-principles EOS results, the principal shock Hugoniot curve of silicon for pressures varying from 1 Mbar to above 10 Gbar was derived. We find that silicon is 20% or more softer than what was predicted by widely-used EOS models. Existing high-pressure experimental data (P = 1 - 2 Mbar) seem to indicate this softening behavior of Si, which calls for future strong-shock experiments (P > 10 Mbar) to benchmark our results. Comment: 30 pages, 6 figures |
| Databáze: | arXiv |
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