Two-level iterative solver for linear response time-dependent density functional theory with plane wave basis set.

Abstract

We present a two-level iterative solver for linear response time-dependent density functional theory by combining two forms of the Casida equation in the Kohn-Sham orbital representation and in Hutter's formulation. This two-level iterative solver has been implemented with the plane wave pseudopotential method for excited-state simulations of molecular and low-dimensional solid materials. Numerical studies with the Davidson algorithm demonstrate that this two-level iterative solver yields excited-state properties for molecules (benzene C6H6 and fullerene C60) and low-dimensional semiconductors [two-dimensional molybdenum disulfide MoS2 monolayer and rutile titanium dioxide TiO2(110) surface] with significantly reduced computational cost and storage requirement compared with standard iterative algorithms. We apply our approach to investigate the photoinduced charge separation of methanol molecules adsorption on the rutile TiO2(110) surface from the exciton perspective and validate that the photogenerated hole can be captured by methanol molecules.