We apply the adiabatic time-dependent density functional theory (TDDFT) to the generation
of coherent optical phonons in Si crystals by intense laser pulses. The theory reproduces the
main phenomena observed experimentally: dependence on polarization, strong growth at
the direct band gap, and the change in phase from below to above the band gap. Both show
that two mechanisms invoked in phenomenological theory, namely, impulsively stimulated
Raman scattering and displacive excitation, are present in the TDDFT. The calculated phase …

We apply the time-dependent density functional theory (TDDFT) to the generation of
coherent optical phonons in Si and Sb crystals. The computations are carried out by real-
time evolution of the orbital wave functions on a coordinate-space mesh. The theory
reproduces the main phenomena observed experimentally: dependence on polarization,
strong growth at the direct band gap, and the change in phase from below to above the band
gap. Comparing with more phenomenological models, we find that the TDDFT supports the …