Ultrasoft pseudopotentials in time-dependent density-functional theory

We describe an efficient formulation allowing the use of ultrasoft pseudopotentials (USPPs) in plane wave based time-dependent density-functional theory. The practical steps required to implement USPP functionality within real time propagation schemes and linear-response schemes based on Lanczos algorithms are provided. The functioning of the methodology is demonstrated by calculations of the optical absorption spectra of the fullerene C(60), using both real time propagation and the Lanczos/linear-response approaches. Comparisons between the rates of convergence of the optical spectra with the number of applications of the Hamiltonian required in calculations with ultrasoft pseudopotentials and norm-conserving pseudopotentials show clearly the benefits provided by the use of USPP.