Development of modified molecular dynamics method for metal: materials processing phenomena by ultrashort-pulse laser (report 1)

摘要

Recently, short-pulse lasers have been applied to microprocessing in the field of various industries. It becomes more difficult to experimentally observe the microprocessing phenomena as pulse width becomes short. Numerical analysis with a continuum model has a limit in elucidation of such phenomena, therefore, computer simulations at the atomic or molecular level must be important. The authors have carried out the molecular dynamics simulation for the first time in the field of laser materials processing and have been making fusion and evaporation phenomena clear at the atomic level. In this paper, a modified molecular dynamics method for metal was developed, in which calculation of the molecular dynamics is carried out compensating the heat conduction by free electrons at each time step. Its validity was confirmed by calculating thermal conductivity and thermal diffusivity. Pulse width dependence of damage threshold was also investigated.