Ab initio Simulation of Optical Limiting: The Case of Metal-Free   Phthalocyanine
  We present a fully ab initio, non-perturbative description of the optical limiting properties of a metal-free phthalocyanine, by simulating the effects of a broadband electric field of increasing intensity. The results confirm reverse saturable absorption as leading mechanism for optical limiting phenomena in this system and reveal that a number of dipole-forbidden excitations are populated by excited-state absorption, at more intense external fields. The excellent agreement with the experimental data supports our approach as a powerful tool to predict optical limiting, in view of applications. 
Caterina Cocchi, Deborah Prezzi, Alice Ruini, Elisa Molinari and Carlo   A. Rozzi
cond-mat.mtrl-sci cond-mat.soft