Theoretical Study of Electron-Phonon Interaction in ZrB2 and TaB2

Using full-potential, density-functional-based methods we have studied electron-phonon interaction in ZrB2 and TaB2 in P6/mmm crystal structure. Our results for phonon density of states and Eliashberg function show that the electron-phonon coupling in ZrB2 is much weaker than in TaB2. In particular, we find that the average electron-phonon coupling constant \lambda is equal to 0.14 for ZrB2 and 0.72 for TaB2. The solutions of the isotropic Eliashberg gap equation indicate no superconductivity for ZrB2 but a superconducting transition temperature Tc of around 12 K for TaB2 with \mu* ~0.16.