title: Linear optical response of finite systems using multishift linear system solvers.
abstract: We discuss the application of multishift linear system solvers to linear-response time-dependent density functional theory. Using this technique the complete frequency-dependent electronic density response of finite systems to an external perturbation can be calculated at the cost of a single solution of a linear system via conjugate gradients. We show that multishift time-dependent density functional theory yields excitation energies and oscillator strengths in perfect agreement with the standard diagonalization of the response matrix (Casida's method), while being computationally advantageous. We present test calculations for benzene, porphin, and chlorophyll molecules. We argue that multishift solvers may find broad applicability in the context of excited-state calculations within density-functional theory and beyond.
authors.affiliation: Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom.
authors.forename: Hannes
authors.initials: H
authors.lastname: Hübener
authors.affiliation: Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom.
authors.forename: Feliciano
authors.initials: F
authors.lastname: Giustino