Liquid metal embrittlement of an otherwise ductile material is an en vironmentally induced fracture phenomenon characterized by poten tially high brittle crack propagation rate and deleterious effects on mechanical properties. Its phenomenology is still not well understood, in particular in terms of prediction of sensible couples and about the detailed intergranular fracture mechanisms. Here we will report on the study in the copper systems via both an energetic and QM/MM approaches at the atomic level to predict the sensitivity of model ma terials to liquid metal embrittlement. The main goal is to try to link micro-testing (flexion in FIB prepared samples or by in-situ TEM) to a sound modelling at the atomistic scale via fracture mechanics type sollicitations. The progress towards predictability of liquid metal em brittlement systems and understanding of fracture mechanisms will be presented along with a vision about their experimental validation.