The 6th International Conference on Matter and Radiation at Extremes (ICMRE2023)

46 / 2023-04-08 18:01:03

Non-equilibrium energy transfer in laser-excited solids and warm dense matter

Radiation and Hydrodynamics > High energy density science and warm dense matter-I

The electron-ion interaction plays a central role in the energy relaxation processes and ultra-fast structural dynamics in laser-irradiated materials [1-3]. The accurate prediction of temperature-dependent electron-ion coupling factors G_ei(T_e, T_i) in a transient excited solid and warm dense matter state out-of equilibrium still remains and open and challenging problem even though many theoretical efforts have been made [4,5]. Here, we take a fully first-principles scheme combining finite temperature DFT-MD and corresponding DFPT to determine the electron-ion coupling. We highlight calculations of the temperature-dependent Eliashberg function and electron density of states for solid and warm dense metals. In the solid regime, we find that, for simple metal aluminum, of the three branch-dependent electron–phonon coupling strengths, the longitudinal acoustic mode plays a dominant role in the electron–phonon coupling for electron temperatures up to T_e = 50,000 K; however, for the transition metal copper with the same fcc structure as aluminum, all partial electron–phonon couplings are of very similar size for electron temperatures below ~30,000 K [6]. We extend our calculations to magnetic metals as well, in which the spin-resolved DFT should be taken into consideration. Further, we extend our study of into the warm dense matter regime by varying the density and ion temperature. The so obtained electron-ion couplings are thus depending on density, electron temperature and ion temperature. Good agreement of our DFT-MD and DFPT based results can be observed with recent data by Simoni et al. [5]. Our present work provides a rich perspective on the phonon dynamics and establishes a benchmark for estimating this key physical quantity under extreme conditions. This will help to improve our insight into the underlying mechanism of microscopic energy flow in ultra-fast laser–metal interaction.

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[3] Mo, M.; Chen, Z.; Li, R.; Dunning, M.; Witte, B.; Baldwin, J.; Fletcher, L.; Kim, J.; Ng, A.; Redmer,R.; et al., Science 2018, 360, 1451–1455.

[4] Lin, Z.; Zhigilei, L.V.; Celli, V., Phys. Rev. B 2008, 77, 075133.

[5] Simoni, J.; Daligault, J., Phys. Rev. Lett. 2019, 122, 205001.

[6] Zhang, J.; Qin, R.; Zhu,W.; Vorberger, J., Materials 2022,15, 1902. https://doi.org/10.3390/ma15051902.