Ab initio simulation of laser-induced transformations in fullerite

We studied by ab initio molecular dynamics the modifications induced on ful lerite by irradiation with ultrashort, very intense laser pulses. We identi fied the threshold for the nonthermal cage opening of the C-60 molecules th at is the analog of the laser-induced nonthermal melting observed in semico nductors and graphite. The new phase formed by the nonthermal coalescence o f the C-60 molecules is fluidlike and mainly formed by small chains of twof old-coordinated atoms. An estimate of the threshold laser fluence for the n onthermal transformation is given.