Ab Initio Calculations of Transient Optical Properties of Metals under Femtosecond Laser Irradiation
Résumé
Ultrashort pulse laser irradiation can generate, under particular conditions, structuring of materials on the nanoscale. In this respect, localized ablation on subdiffraction limit scales or ripples formation have found a particular interest in tribology, wettability or anti-counterfeiting domains. The achievement of nanostructuring is governed by material response under thermal nonequilibrium [1] which still have to be clearly understood. The present work is a first-principles study of simple metal properties (Al, Ni, Cu and Ti) in nonequilibrium conditions. Density functional theory is used in order to perform ground states calculations, response-function calculations and ab initio molecular dynamic simulations. From these calculations, we derive nonequilibrium material properties for optical and thermal models. We also evaluate the stability of materials under irradiation [2] or compute optical index and optical conductivities from the resolution of time-resolved Kubo-Greenwood formalism. [1] J. P. Colombier, et al., J. Appl. Phys. 111, 024902 (2012) [2] V. Recoules, J. Clérouin, G. Zérah, P.M. Anglade and S. Mazevet, PRL 96, 055503, (2006)