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Thermal excitation of d band electrons in Au: implications for laser-induced phase transformations

机译：AU中D带电子的热激励：激光诱导相变的影响

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The temperature dependences of the electron heat capacity and the electron-phonon coupling factor are investigated for Au based on the electron density of states obtained from ab initio electronic structure calculations. Thermal excitation of d band electrons leads to a significant (up to an order of magnitude) increase in the electron-phonon coupling factor and makes a considerable contribution to the electron heat capacity in the range of electron temperatures typically realized in femtosecond laser material processing applications. Simulations performed with a combined atomistic-continuum method demonstrate that the increase in the strength of the electron-phonon coupling at high electron temperatures leads to a faster lattice heating, generation of stronger thermoelastic stresses, and a significant decrease in the time of the onset of the melting process. The timescale of the melting process predicted in the simulation accounting for the thermal excitation of d band electrons is in excellent agreement with the results of recent time-resolved electron diffraction experiments. A simulation performed with commonly used approximations of a constant electron-phonon coupling factor and a linear temperature dependence of the electron heat capacity, on the other hand, significantly overpredicts the time of the beginning of the melting process, supporting the importance of the electron density of states effects and thermal excitation of lower band electrons for realistic modeling of femtosecond pulse laser processing.
机译：电子热容量和电子 - 声子耦合因子的温度依赖性是为金基于从从头电子结构计算得到的状态的电子密度上的影响。 d带电子引线在电子 - 声子耦合因子a显著（高达一个数量级）的增加的热激发，使在电子温度的范围内的电子的热容量相当大的贡献通常在飞秒激光材料加工应用实现。模拟用的组合原子论-连续方法进行证明在电子 - 声子的强度的增加在高温电子温度引线耦合到一个更快的晶格加热，产生更强的热应力，并且在发病时的显著减少熔化过程。在模拟中占d带中的电子的热激发所预测的熔化过程的时间尺度与最近时间分辨电子衍射实验的结果非常一致。仿真具有恒定电声子耦合因子和电子热容量的线性温度依赖性的常用近似值进行，另一方面，显著overpredicts熔化过程的开始之时，支撑所述电子密度的重要性的状态的效果和低带中的电子为飞秒脉冲激光加工的现实建模的热激发。

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