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MO: Fachverband Molekülphysik

MO 11: Theoretical Approaches

MO 11.3: Vortrag

Dienstag, 6. März 2018, 14:30–14:45, PA 1.150

Non-adiabatic molecular dynamics with long-range corrected tight-binding DFT — •Alexander Humeniuk and Roland Mitrić — Julius-Maximilians-Universität Würzburg

The efficiency of tight-binding DFT permits non-adiabatic molecular dynamics simulation on larger systems as would be possible with full TD-DFT. However, large molecular assemblies pose new problems to DFT(B) and surface hopping, which are absent in smaller molecules: For weakly coupled chromophores, DFT with a local exchange-correlation-functional predicts unphysically low charge-transfer states. Also many degenerate electronic states appear due to excitations localized on the various identical subunits, which renders the adiabatic picture partly useless and causes numerical instabilities.

We present a software package which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of charge-consistent tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton’s equations of motion for the nuclei together with the electronic Schrödinger equation. Non-adiabatic effects are included by surface hopping.

As an example, the program is applied to the optimization of excited states and non-adiabatic dynamics of polyfluorene.