Vlasov Simulation of Electron Dynamics in Solids Under Intense Laser Fields

Metal hyper-micro-structuring technique using ultra-short intense pulsed lasers has been investigated from both sides of experiments and simulations [1] , [2] . Ultrafast (fs-ps) laser micromachining is initiated by optical electron excitation, then, energy transfer from the hot electrons to the lattice. As a result, the material gets into phase or structural transition, leading to ablation or drilling, suppressing heat-affected zones. While plasma or continuum models have often been used to simulate such processes [1] , [3] , proceeding comprehension so far. They have difficulties in examining initial transient dynamics before the local thermodynamic equilibrium is reached. The ab initio quantum method based on the time-dependent density functional theory (TDDFT) [4] is difficult to apply to ps-scale simulations or laser parameter optimization because of high computational cost and insufficient account of many-body correlation. In this work, to overcome these difficulties, we propose an approach based on the Vlasov equation with the local-density-approximation (LDA) exchange-correlation potential taken from the density functional theory. We extend the pseudo particle method, previously used to numerically solve the Vlasov-LDA equation for isolated systems [5] , to describe electron dynamics in periodic systems under intense laser fields. The calculated optical conductivity, refractive index, extinction coefficient, and reflectivity as well as energy absorption for bulk aluminum without many-body collisions are in excellent agreement with the TDDFT results and experimental references.