• Matter and Radiation at Extremes
  • Vol. 7, Issue 3, 036901 (2022)
Jacob M. Molinaa) and T. G. White
Author Affiliations
  • University of Nevada, Reno, Nevada 89557, USA
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    DOI: 10.1063/5.0073217 Cite this Article
    Jacob M. Molina, T. G. White. A molecular dynamics study of laser-excited gold[J]. Matter and Radiation at Extremes, 2022, 7(3): 036901 Copy Citation Text show less

    Abstract

    The structural evolution of laser-excited systems of gold has previously been measured through ultrafast MeV electron diffraction. However, there has been a long-standing inability of atomistic simulations to provide a consistent picture of the melting process, leading to large discrepancies between the predicted threshold energy density for complete melting, as well as the transition between heterogeneous and homogeneous melting. We make use of two-temperature classical molecular dynamics simulations utilizing three highly successful interatomic potentials and reproduce electron diffraction data presented by Mo et al. [Science 360, 1451–1455 (2018)]. We recreate the experimental electron diffraction data, employing both a constant and temperature-dependent electron–ion equilibration rate. In all cases, we are able to match time-resolved electron diffraction data, and find consistency between atomistic simulations and experiments, only by allowing laser energy to be transported away from the interaction region. This additional energy-loss pathway, which scales strongly with laser fluence, we attribute to hot electrons leaving the target on a timescale commensurate with melting.
    ε=ηE,

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    Ce(Te)Tet=gei(TeTi),

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    mvit=Fiγvi+fL(Tt),

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    fL(Tt)=0,

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    fL(Tt)fL(Tt)=2γkBTeδ(tt).

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    dσineldΩ=AQ411(1+BQ2)2+mQ+c

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    Jacob M. Molina, T. G. White. A molecular dynamics study of laser-excited gold[J]. Matter and Radiation at Extremes, 2022, 7(3): 036901
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