  The femtosecond laser pulse heating of silver film is investigated by
performing quantum mechanics (QM), molecular dynamics (MD) and two temperature
model (TTM) integrated multiscale simulation. The laser excitation dependent
electron thermophysical parameters (electron heat capacity, electron thermal
conductivity, and effective electron-phonon coupling factor) are determined
from ab initio QM calculation, and implemented into TTM description of electron
thermal excitation, heat conduction, as well as electron-phonon coupled thermal
energy transport. The kinetics of atomic motion is modeled by MD simulation.
Energy evolution of excited electron subsystem is described by TTM in
continuum. The MD and TTM are coupled by utilizing the effective
electron-phonon coupling factor. Laser heating with varying laser fluence is
systematically studied to determine the thresholds of the homogeneous melting
and ablation. The thermal ablation induced by faster expansion of locally and
excessively superheated silver is reported. This paper provides a basis for
interpreting the phase change process induced by laser heating, and facilitates
the advancement of femtosecond laser pulse processing of material.
