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 Sánchez-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.
Second, a more extensive paper exploring how far we can use information from excited-state wavefunction analysis tools to understand excitation energies beyond the molecular orbital picture. The energy of a correlated electron-hole pair is derived using diagrammatic techniques and this information is further used for a graphical depiction in terms of different charge distributions and their electrostatic potentials. Doing so turned out not as easy as hoped for but was very exciting. Find more here: Toward an Understanding of Electronic Excitation Energies Beyond the Molecular Orbital Picture by P. Kimber and F. Plasser.
Tomorrow Felix will give a talk at the New Horizons in Materials Modelling 2020 taking place in York. Title: A toolbox for analysing structure-property relationships in functional molecules interacting with light.
Tomorrow, Felix will give a talk at the Zernike Institute for Advanced Materials, Groningen. The talk is entitled: Understanding electronic excitation energies within and beyond the molecular orbital picture. It discusses how we can understand excited-state energies beyond simply looking at orbitals and their energies.
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.
Version 2.0 of the TheoDORE wavefunction analysis package has been released, download below. The two main features of TheoDORE 2.0 are the computation of conditional electron densities and compatibility with python3.
Conditional electron densities can be used for the visualisation of excited-state electron correlation, see ChemPhotoChem (2019). Below, the application of this method to a PPV oligomer is shown. Here, the probe hole (red) is always fixed on the terminal phenyl ring and the different shapes for the conditional electron density (blue) for the first six excited states is observed. One can see that for the different states the electron is either repelled, attracted or unaffected by the hole.
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.