Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Focused Session: Frontiers of Electronic Structure Theory 2 (jointly with HL and O)

TT 22.4: Talk

Monday, March 11, 2013, 16:45–17:00, H36

Linear-scaling time dependent density-functional theory in the linear response formalism — •Tim J. Zuehlsdorff, Nicholas D. M. Hine, James S. Spencer, Nicholas M. Harrison, and Peter D. Haynes — Imperial College London, UK

In recent years, linear-scaling approaches to density-functional theory have enabled the computation of ground-state properties of large nanostructures and biomolecules. While these methods are now well established, the linear-scaling computation of excited state properties via time-dependent density-functional theory (TDDFT) in the linear response regime is less developed.

In this talk we will present an implementation of TDDFT in the linear response formalism, enabling the computation of low-energy optical absorbtion spectra for large molecules and nanostructures. The method avoids any explicit reference to canonical representations of either occupied and unoccupied Kohn-Sham states and thus achieves linear-scaling computational effort with system size. In contrast to conventional localised orbital formulations where a single basis set is used to represent the occupied and unoccupied Kohn-Sham states, we make use of two sets of in-situ optimised localised orbitals, one for the occupied and one for the unoccupied Kohn-Sham space. The double basis set approach avoids known problems of representing the unoccupied space with localised orbitals optimised for the occupied space, while the in-situ optimisation procedure allows for efficient calculations with a minimal set of basis functions. The method is applied to a number of large-scale test systems in order to demonstrate its validity.