# Resonance energy transfer in orthogonally arranged chromophores: a question of molecular representation

## TL;DR

The paper shows that standard energy transfer theory can explain energy transfer in orthogonally arranged chromophores when thermal vibrations are considered.

## Contribution

The novelty lies in demonstrating that conventional Förster theory remains valid without extensions by using thermal ensemble structures.

## Key findings

- Thermal vibrations affect transition dipole alignment and energy transfer rates in orthogonal systems.
- Standard Förster theory accurately describes energy transfer when using thermal ensemble structures.
- No formal expansion of Förster theory is needed when chromophore representation is improved.

## Abstract

Energy transfer between orthogonally arranged chromophores is typically considered impossible according to conventional Förster resonance energy transfer theory. Nevertheless, the disruption of orthogonality by nuclear vibrations can enable energy transfer, what has prompted the necessity for formal expansions of the standard theory. Here, we propose that there is no need to extend conventional Förster theory in such cases. Instead, a more accurate representation of the chromophores is required. Through calculations of the energy transfer rate using structures from a thermal ensemble, rather than relying on equilibrium geometries, we show that the standard Förster resonance energy transfer theory is still capable of describing energy transfer in orthogonally arranged systems. Our calculations explain how thermal vibrations influence the electronic properties of the states involved in energy transfer, affecting the alignment of transition dipole moments and the intensity of transitions.

Through calculations of the energy transfer rate using structures from a thermal ensemble, we show that the standard Förster resonance energy transfer theory is capable of describing energy transfer in orthogonally arranged systems.