Shirin Faraji

We present a computational investigation of the parity-violating contributions to the vibrational transitions and nuclear magnetic resonance shieldings of helical osmocene. A number of promising transitions within the spectral window of currently available sub-Hz metrology-grade lasers are identified, exhibiting high intensities and parity violation shifts of up to 7 Hz. We discuss the prospects for the synthesis of this compound and for subsequent ultra-precise mid-IR spectroscopy toward the first detection of parity violation in a chiral molecule.

The laser-induced fluorescence spectrum (LIF) of 1,2-dicyanobenzene (1,2-DCB) has been recorded and analyzed by comparison to an \textit{ab initio} normal mode analysis. Franck-Condon (FC) fits of vibronic intensities from single vibronic level fluorescence (SVLF) spectra have been used to determine the geometry change of 1,2-DCB upon excitation to the lowest excited singlet state (S$_1$). In contrast to the predictions of \textit{ab initio} calculations, which result in preservation of the C$_{2v}$-symmetry upon electronic excitation, we find a reduction in the symmetry to C$_s$ from the FC analysis. We explain this finding, by the excitation of two different locally excited states, whose superposition results in a C$_{2v}$-symmetric structure as predicted by \textit{ab initio} theory.

Theory meets experiment: Prof. Andrew P. Monkman (Durham University, UK), Prof. Christel Marian (University Düsseldorf, DE), and Prof. Hironori Kaji (Kyoto University, JP) at the 14th Int’l Electroluminescence & Optoelectronic Conference, Kyoto.

We demonstrate here that light can be used to modulate proton transport in polymeric soft materials using a polymerizable molecular photoswitch. To this end, we designed a merocyanine metastable-state photoacid, which we used as building block to prepare a series of light-responsive polymers. We confirm the metastable character of the proposed monomer, and we elucidate its potential energy surface and the energies associated with its photoisomerization using quantum mechanical calculations. Interestingly, we found that when incorporated into a polymeric matrix, a photoacid loading effect impacts the photochrome’s photochromism and induces significant changes to the polymer nanostructure. Moreover, we show that the presence of photoacid imparts proton transport properties to an otherwise insulating polymers and we found a clear relationship between the amount of responsive monomer and the material’s proton conductivity. We found that irradiation of polymeric films induces a reversible decrease in conductivity as the photoacid releases protons and undergoes a change in net charge which we demonstrate using a hydrogel actuator. Our study establishes a platform for the design of out-of-equilibrium, photo-modulated proton-conductive materials, offering new opportunities for responsive materials and iontronics applications.

Left: blend system with a close-up of the donor–acceptor dimer geometries modelled within a via TDDFT/MD approach. Center: sketch of the charge-transfer model. Right: charge-transfer state wave packet dynamics and Wigner functions.

Quantum coherences play a central role in a broad range of fields, including functional energy materials, biological systems, and molecular quantum information science. Coherences encode critical information about the phase and dynamics of a system, and their interaction with its environment. Particularly, the ultrafast charge transfer process between electron donor and acceptor species in functional energy materials is influenced by vibronic coherences. A key limitation arises from the dephasing of coherences due to dissipation, causing loss of information and limiting applications of molecular systems. Extending and controlling coherence lifetimes would enable the rational design of smarter materials with optimised properties. Here we introduce a novel idea using chirped excitations as a pathway to extend quantum coherence lifetimes, enhancing their robustness against dissipation. A detailed analysis of the light-induced molecular quantum dynamics and wave packet evolution from first-principles models constructed at the donor–acceptor heterojunction of an organic photovoltaic blend is discussed. We demonstrate that tuning the chirp of the excitation pulse, vibronic coherence lifetimes can be extended up to the picosecond timescale. Chirped excitations also enable tunable spatial localisation of the induced wave packet, with localisation controlled by the chirp intensity. These effects are observed consistently across different donor–acceptor adducts selected from the molecular dynamics structure of the blend. Our results introduce a new degree of freedom for coherent control in molecular systems, offering a promising pathway toward the development of advanced functional energy materials and applications in molecular quantum information science.

Molecular dynamics, umbrella sampling, and QM/MM were used for modelling binding, permeation, and photophysics of photoswitchable psychedelics, identifying features that tune absorption spectra and enhance receptor and membrane interactions.

Different trajectory-based methods for nonadiabatic molecular dynamics are implemented in the PySurf code. The methods can be seamlessly applied and compared on the same systems.

Molecular‐level understanding of photoinduced processes is critically important for breakthroughs in transformative technologies utilizing light, ranging from photomedicine to photoresponsive materials. Theory and simulation play a crucial role in this task. Despite great advances in hardware and computational methods, the theoretical description of photoinduced phenomena in the presence of complex environments and external photoexcitation conditions still poses formidable challenges for theoreticians and there are numerous formal and computational difficulties that must be overcome. The development of predictive, accurate, and at the same time, computationally efficient theoretical approaches to describe complex problems in photochemistry and photophysics is an active field of research in contemporary theoretical and computational chemistry. In this advanced review, we discuss modern computational advances and novel approaches that have been recently developed in excited‐electronic structure methods, and multiscale modeling, with a special emphasis on coupled electron‐nuclear dynamics and spectroscopy, from fully quantum to semi‐classical methodologies—including dissipative effects, the explicit light field interaction, femtosecond time‐resolved spectroscopy, and software infrastructure.This article is categorized under: Software > Quantum Chemistry Electronic Structure Theory > Combined QM/MM Methods Theoretical and Physical Chemistry > Spectroscopy Software > Molecular Modeling

Psychedelic compounds can induce rapid-acting and long-lasting antidepressant benefits. Understanding the role of their hallucinatory effects is crucial for shaping the future trajectory of antidepressant drug development. Photoswitchable compounds targeting the 5-HT2AR offer precise spatio-temporal control over the activation of different downstream pathways. In this work, we computationally discovered PQ-azo-N,N-DMT (34), a photoswitch with improved features compared to the previously synthesized azo-N,N-DMT (1). The new compound shows tight binding to the 5-HT2AR, retaining all important interactions of lysergic acid diethylamide (LSD), exhibits positive membrane permeability, and has a strong red-shifted absorption that would allow photocontrol in the visible spectrum.