AB-INITIO MOLECULAR-DYNAMICS SIMULATION OF LASER MELTING OF GRAPHITE

The method of ab initio molecular dynamics, based on finite temperatur e density functional theory, is used to simulate laser heating of grap hite. We find that a sufficiently high concentration of excited electr ons dramatically weakens the covalent bond. As a result the system und ergoes an ultrafast melting transition to a metallic state. This proce ss appears to be similar to, although considerably faster than, laser melting of silicon. The properties of the laser-induced liquid phase o f carbon are found to depend crucially on the level of electronic exci tation. All these features are in qualitative agreement with the exper imental behavior. (C) 1998 American Institute of Physics.