title: Efficient calculation of electronic absorption spectra by means of intensity-selected time-dependent density functional tight binding.
abstract: During the last two decades density functional based linear response approaches have become the de facto standard for the calculation of optical properties of small- and medium-sized molecules. At the heart of these methods is the solution of an eigenvalue equation in the space of single-orbital transitions, whose quickly increasing number makes such calculations costly if not infeasible for larger molecules. This is especially true for time-dependent density functional tight binding (TD-DFTB), where the evaluation of the matrix elements is inexpensive. For the relatively large systems that can be studied the solution of the eigenvalue equation therefore determines the cost of the calculation. We propose to do an oscillator strength based truncation of the single-orbital transition space to reduce the computational effort of TD-DFTB based absorption spectra calculations. We show that even a sizable truncation does not destroy the principal features of the absorption spectrum, while naturally avoiding the unnecessary calculation of excitations with small oscillator strengths. We argue that the reduced computational cost of intensity-selected TD-DFTB together with its ease of use compared to other methods lowers the barrier of performing optical property calculations of large molecules and can serve to make such calculations possible in a wider array of applications.
authors.affiliation: Scientific Computing & Modelling NV , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.|Department of Theoretical Chemistry, VU University Amsterdam , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Robert
authors.initials: R
authors.lastname: Rüger
authors.affiliation: Scientific Computing & Modelling NV , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: van Lenthe
authors.affiliation: Scientific Computing & Modelling NV , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: You
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Chemistry, University of Calgary , 2500 University Drive, N.W., T2N 1N4 Calgary, Canada.
authors.forename: Johannes
authors.initials: J
authors.lastname: Frenzel
authors.affiliation: School of Engineering and Science, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heine
authors.affiliation: Department of Theoretical Chemistry, VU University Amsterdam , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Lucas
authors.initials: L
authors.lastname: Visscher