Ab Initio Calculations of Transient Optical Properties of Metals under Femtosecond Laser Irradiation

Abstract : 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)