Messanae Universitas Studiorum

Density-functional perturbation theory goes time-dependent

Baroni, Stefano and Rocca, Dario and Gebauer, Ralph (2008) Density-functional perturbation theory goes time-dependent. Atti della Accademia Peloritana dei Pericolanti - Classe di Scienze MM.FF.NN., LXXXVI (2). ISSN 1825-1242

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Abstract

The scope of time-dependent density-functional theory (TDDFT) is limited to the lowest portion of the spectrum of rather small systems (a few tens of atoms at most). In the static regime, density-functional perturbation theory (DFPT) allows one to calculate response functions of systems as large as currently dealt with in ground-state simulations. In this paper we present an effective way of combining DFPT with TDDFT. The dynamical polarizability is first expressed as an off-diagonal matrix element of the resolvent of the Kohn-Sham Liouvillian super-operator. A DFPT representation of response functions allows one to avoid the calculation of unoccupied Kohn-Sham orbitals. The resolvent of the Liouvillian is finally conveniently evaluated using a newly developed non-symmetric Lanczos technique, which allows for the calculation of the entire spectrum with a single Lanczos recursion chain. Each step of the chain essentially requires twice as many operations as a single step of the iterative diagonalization of the unperturbed Kohn-Sham Hamiltonian or, for that matter, as a single time step of a Car-Parrinello molecular dynamics run. The method will be illustrated with a few case molecular applications.

Item Type: Article
Subjects: M.U.S. - Contributi Scientifici > 04 - Scienze della terra
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali
Depositing User: Mr Nunzio Femminò
Date Deposited: 26 Nov 2009
Last Modified: 13 Apr 2010 11:14
URI: http://cab.unime.it/mus/id/eprint/538

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