Noble metal nanoparticles exhibit unique optical and catalytic properties which are suitable for numerous applications in areas such as catalysis, imaging and biosensors. Theoretical treatment of such nanoparticles have employed a large class of methodologies ranging from classical Mie theory to ab initio methods such as DFT. While the classical methods can provide useful information for large nanoparticles, they are not appropriate for systems where the quantum effects become dominant. In such cases, DFT and other ab initio methods can be employed to investigate the quantum nature of the system. However, the application of these methods are usually feasible for systems with 200-300 atoms, and approximations are often needed for larger nanoparticles.<br/>In this contribution, we investigate the accuracy and efficiency of density functional tight-binding (DFTB) and time-dependent DFTB (TD-DFTB) methods for the prediction of optical and electronic properties of small to medium sized silver nanorods. For smaller systems, the calculated absorption spectra and electronic structures at the DFTB level are compared to those obtained with DFT methods as benchmark cases. Furthermore, the absorption spectra of the dimers of silver nanorods are investigated for different particle sizes and different inter-particle distances with DFTB-based methods. Our results show that there is a good qualitative agreement between DFT and DFTB for the investigated systems, and DFTB and TD-DFTB can be utilized to explore the electronic structure and optical properties of silver nanoparticles with 20-2000 atoms.

TD-DFTB investigation of electronic structure and optical properties of silver nanorods and nanorod dimers

255th National Meeting (2018)

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