Efficient Calculation of Electronic Absorption Spectra by Means of IntensitySelected TDDFTB
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 mediumsized molecules. At the heart of these methods is the solution of an eigenvalue equation in the space of singleorbital transitions, whose quickly increasing number makes such calculations costly if not infeasible for larger molecules. This is especially true for timedependent density functional tight binding (TDDFTB), 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 singleorbital transition space to reduce the computational effort of TDDFTB based absorption spectra calculations. We show that even a sizeable 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 intensityselected TDDFTB together with its ease of use compared to other methods lowers the barrier of performing optical properties calculations of large molecules, and can serve to make such calculations possible in a wider array of applications.
 Publication:

arXiv eprints
 Pub Date:
 September 2014
 DOI:
 10.48550/arXiv.1409.4521
 arXiv:
 arXiv:1409.4521
 Bibcode:
 2014arXiv1409.4521R
 Keywords:

 Physics  Chemical Physics
 EPrint:
 17 pages, 7 figures