Linear-response calculation of the Coulomb pseudopotential mu* for Nb

We perform first-principles theoretical calculations of the Coulomb pseudopotential mu* for the d-band metal Nb using a dielectric matrix approach. Although localized d electrons give rise to a large local-field effect that increases the dielectric screening and reduces the strength of mu*, the enhancement of mu* due to the exchange-correlation effect is more significant, resulting in a value of 0.14 for mu*, in good agreement with what is usually assumed.