Effect of intense laser irradiation on the structural stability of 3C-SiC

Using the linear response method based on the density functional perturbation theory, we simulate the effect of intense laser irradiation on the zinc-blende structural stability of silicon carbide crystal. By calculating the phonon dispersion curves for the 3C-SiC crystal of the zinc-blende structure at different electronic temperatures, we find that the transverse acoustic phonon frequencies of 3C-SiC become imaginary as the electron temperature increases. The critical electronic temperature is 3.395 eV. This means that the lattices of 3C-SiC become unstable under the intense laser irradiation. These results are very similar to the previous results for the diamond structure(C and Si) and the zinc-blende structure (GaAs and InSb). In an electron temperature range of 0-4.50 eV, the LO-TO splitting at gradually increases with the increase of electronic temperature. When the electron temperature is beyond 4.50 eV, the splitting decreases. The results indicate that only under the intense enough laser irradiation, the ionic strength can be weakened by the electronic excitation.