Directional excitations in photosensitisers

Characterising excited states in transition metal complexes by looking at pictures of orbitals can be a tedious task. Even more, it is hard to eliminate personal in the process and produce quantitative results. In a study led by Pedro S├ínchez-Murcia from the University of Vienna, we have taken a closer look at this problem in the case of various substituted complexes deriving from the archetype Ru(bpy)3 with the aim of quantifying how different substituents influence the localisation of the excited electron. The result is presented in the article “Orbital-free photophysical descriptors to predict directional excitations in metal-based photosensitizers,” which just appeared in Chemical Science.

Talk: Excited states of transition metal complexes

On Thursday, 20/06, Felix will give a talk at the CECAM workshop on Theoretical and Computational Inorganic Photochemistry in Toulouse. This talk will discuss how excited states in transition metal complexes can be assigned completely automatically without ever looking at an orbital. It is shown how this method can be used for a high-throughput analysis of excited states as well as for benchmarking excited-state computations. Finally, a quick outlook will be given on how correlation effects can be visualised using a newly developed tool for computing conditional electron/hole densities.

You can download the slides here:

Preprint: Details in the surface hopping algorithm

Having discussed the influence of electronic structure methods in surface hopping dynamics in the last post and paper, we can now proceed to the surface hopping algorithm itself. To our surprise, algorithmic details such as the decoherence correction (energy-based decoherence or augmented FSSH), momentum rescaling and the treatment of frustrated hops can make a big difference. This is what we investigated in our new preprint “Strong Influence of Decoherence Corrections and Momentum Rescaling in Surface Hopping Dynamics of Transition Metal Complexes” available on ChemArxiv.

To have a well-defined reference, we used our new implementation of vibronic coupling models for surface hopping, which allows us to have a one-to-one comparison with accurate quantum dynamics computed at the MCTDH level of theory. As model system, we used a rhenium complex and studied its ultrafast intersystem crossing dynamics from the singlet to the triplet manifold following previous studies by our collaborators in Strasbourg [JCTC (2017), PCCP (2018)].

Talk at QBIC IV in Bath

On 5 September, Felix Plasser will give a talk entitled “Transition Metal Complex Excited States: Turning Numbers into Chemical Insight” at the Quantum-Bio-Inorganic Chemistry Conference IV in Bath. The talk will discuss the automatic assignment of excited-state character for transition metal complexes and present some recent results about using conditional electron densities for visualising excited-state correlation effects.

You can download the slides here: