Atomistic modeling of quantum processes in nanoscale devices DFTB+: Applications to device and excited state simulations of nanomaterials

ABSTRACT

The new release of DFTB+ as a density-functional (DFT)-based approach, combining DFT-accuracy and Tight-Binding (TB) efficiency, is reported; http//:www.dftb.org. Methodological details and recent extensions to improve reliability and accuracy will be described. Advanced functions include spin degrees of freedom, time dependent methods for excited states, non-adiabatic electron-ion dynamics, and quantum transport calculations under open boundary conditions using non-equilibrium Green´s function methods. The major focus of the talk will be on the time-dependent DFTB extensions and implementation of the electron-photon interaction for studying photo-voltaic and optoelectronic devices. In addition, the TD-DFTB implementation in real time domain allows us to study the interaction of ultra-short laser pulses with nanomaterials and hybrid interfaces and to follow the coupled electron-ion dynamics in non-adiabatic molecular dynamics simulations. Applications to laserinduced ultra-fast hot electron injection from metal nanoparticles into adsorbed molecules for driving catalytic reactions will be demonstrated. As an example the Au-TiO2-CO hybrid structure is shown below.