Microscopic analysis of the laser-induced femtosecond graphitization of diamond

We present a theoretical study of ultrafast phase transitions induced by femtosecond laser pulses of arbitrary form. Molecular-dynamics simulations on time dependent potential-energy surfaces derived from a microscopic Hamiltonian are performed. Applying this method to diamond, we show that a nonequilibrium transition to graphite takes place for a wide range of laser pulse durations and intensities. This ultrafast transition (similar to 100 fs) is driven by the suppression of the diamond minimum in the potential-energy surface of the laser excited system. [S0163-1829(99)50730-3].