Influence of phonon stiffness on electron–phonon energy transfer

Electron-phonon coupling plays a crucial role in describing the energy relaxation dynamics of solids excited by ultrafast laser pulses. It depends on electronic and phononic properties to varying degrees for different metals. In many studies of the electron-phonon coupling strength, electronic properties are varied while the phonons are assigned a secondary role. In this work, we study the influence of the phonon stiffness on the electron-phonon coupling parameter. To this end we compare two analytical phonon dispersions, the Debye model and a sinusoidal approach. We find a roughly quadratic scaling of the coupling parameter with the phonon stiffness for both dispersion relations. We present results for gold, aluminum and nickel. For all considered materials, we observe that the high wavenumber phonon modes govern the electron-phonon coupling.