Fig. 7

Phonon dispersion curve of bcc phase at T=0.14 (a), 1.4 (b), 5.4 (c), and 10.9 (d) eV. Comparison of the dashed horizontal line in two up-panel plots indicates phonon softening introduced by electronic temperature. The disappearance of imaginary modes and the hardening of phonons by increasing the electronic temperature can be observed from the plots in the bottom panel.