In this work, we propose an efficient and accurate computational method: using minimal number of molecular diabatic orbitals (essential diabatic orbitals) to calculate the electronic couplings between molecular units in a model organic semiconductor, a thiophene-ring polymer chain to mimic the poly(3-hexylthiophene) (P3HT), a prototype to study optoelectronic and photovoltaic materials. Through a unit block diabatization scheme, a minimal number of thiophene diabatic orbitals (five pi-type orbitals) was selected and employed to calculate the site energies and electronic couplings. We then validated the computations by comparing the results with benchmark density functional theory calculations based on the molecular orbital theory. We systematically investigated how the calculations depended on the basis set and the conformational change of the polymer chain. Meanwhile, using the obtained electronic couplings and site energies, we performed a quantum dynamics simulation to propagate an electronic hole within a polymer chain with 64 thiophene units. Our study establishes a simple, efficient, and robust method for the simulating electron- or hole-transfer processes in organic conducting materials.

Essential diabatic orbital method to calculate electronic couplings between poly-3-hexylthiophene polymer units for charge transfer dynamics simulations

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.