Themed collection Festschrift Wolfgang E. Ernst: Electronic & Nuclear Dynamics in Molecules, Clusters, and on Surfaces

Guest editors, Andreas W. Hauser, Martina Havenith, Markus Koch and Martin Sterrer, introduce this themed issue dedicated to Professor Wolfgang E. Ernst on the occasion of his 70th birthday.

Four kinds of electronic degeneracy or pseudodegeneracy leading to the Jahn-Teller effects.

Weak interactions are essential in modern research and technologies, such as nanocomposite materials, nanometer-sized quantum objects embedded in a host material or van der Waals heterostructures. Various fields address their characterisations and descriptions.

High-level ab initio theory, combined with a full quantum description of the superfluid helium nanodroplet motion, provides evidence for the fundamental mechanism of soft-deposition of Ag and Ag⁺, being the soft-landing favored as the helium nanodroplet size increases.

The photodynamics and B¹A′ ← X¹A′ absorption spectrum of acetone oxide, (CH₃)₂COO, are studied theoretically from first principles.

The stochastic wave function method is proposed to study the diffusion regimes of alkali atoms on metallic surfaces and, in general, surface diffusion.

The PECD of methyloxirane molecules fragmenting along the laser propagation direction (left) shows a strong modulation by the CEP (top) due to the CEP-dependence of the ionization probability from different areas of specific orbitals (bottom right).

The relaxation dynamics of electronically excited ³He and ⁴He clusters and droplets is investigated using time-correlated near-infrared and visible (NIR/VIS) fluorescence excitation spectroscopy.

We have studied 22-oxahemiporphycene molecules by a combination of scanning tunneling microscopy at low temperatures and density functional theory calculations.

The binding and structure of an ordered pyrazine overlayer on graphite are studied with neutron scattering and DFT. We find increased van der Waals bonding and stability of the overlayer compared to benzene, due to the nitrogen atoms in the ring.

The ultrafast relaxation dynamics of excited helium nanodroplets were studied using time-resolved photoelectron spectroscopy. We observed an efficient population of triplet atomic states as well as the formation of the first excimer state of He₂*.

While the self-metalation of 2H-TPP on MgO(001) thin films is mediated by charge transfer, 2H-P self-metalates irrespective of its charge state. The different reactivity is explained based on the molecule-substrate distance.

Electron diffraction of 1,4-dichlorobenzene (C₆H₄Cl₂) clusters embedded in superfluid helium droplets, resulting in the structure evolution of cluster growth.

The ultrafast relaxation within the Q-bands of chlorophyll plays a crucial role in photosynthetic light-harvesting. We investigate this process via nuclear and electronic quantum dynamics on multireference potential energy surfaces.

The mean square displacement of a thermalized CO molecule moving on a copper substrate is evaluated on the basis of a new quantum dynamical approach (Mol. Phys. 119, e1971315, 2021); results at 190 K, the Cu(100) lattice constant a ≈ 256 pm.

Hybrid QM/MM nonadiabatic dynamics of the complex ReCl(CO)₃(bpy) (bpy = 2,2-bipyridine) on spin-mixed potential energy surfaces was carried out in acetonitrile and dimethylsulfoxide.

Collisions of sodium atoms with chlorine atoms and sodium cations with chloride anions are studied by non-adiabatic dynamics. Rate coefficients for mutual neutralisation, chemiionisation, and radiative association are calculated up to 5300 K.

We present femtosecond pump–probe photoionization experiments with indium dimers (In₂) solvated in helium nanodroplets (He_N), and identify an ionization pathway leading to ion ejection from the droplet, enabling ion-electron correlation.

Quantum dynamics simulations demonstrate the presence of ultra-fast non-statistical and slow statistical non-radiative decay and the presence of active and inactive conical intersections in NO₃.

The reaction of LiHMDS with water was investigated at ultra-cold conditions (0.37 K) in superfluid helium nanodroplets using mid IR radiation.

The photodissociation dynamics of Br₂ (B ← X excitation) in helium nanodroplets is much more complex than that of Cl₂, showing very large differences in several key properties. This is the second system investigated theoretically in this context.

Ultracold helium nandroplets are doped by Mg atoms in order to extract ionization potentials of magnesium clusters Mg_N in the size range N = 7–56.

We report the first helium-tagged electronic spectra of cationic adamantane clusters, along with its singly, doubly, and triply dehydrogenated analogues embedded in helium droplets.

Ultrafast internal vibrational relaxation is observed in ammonia's state on a timescale of less than 100 fs. This is a highly surprising observation, and has been revealed through vibronically sensitive time-resolved photoelectron measurements.

The Debye–Waller exponent for Helium atom specular reflection from a conducting surface, when measured as a function of temperature in the linear high-temperature regime, allows for the determination of the surface electron–phonon coupling.

A mixed valence tellurium bridged Fe(II)–Fe(III) complex was studied using correlated ab initio methods. Spectroscopic and magnetic properties have been rationalized considering coupling between spins and vibrations.

Rotationally resolved electronic spectroscopy of phthalocyanine in a supersonic jet has revealed detailed information on the configuration of both electronic states and the corresponding transition dipole moment.

Unusual trapping of an excited state of a dication observed after strong field ionization. Symmetry is responsible for forbidden nonradiative and radiative decay.

A globally accurate PES and dynamics studies for the Ca⁺(²S) + H₂ → CaH⁺ + H reaction.

Understanding the energy-levels and rovibronic spectra of the ethylidyne (CH) and the hydroxyl (OH) radicals is mandatory for a multitude of modelling efforts within multiple chemical, combustion, astrophysical, and atmospheric environments.

DFT calculations assisted by machine-learning models predict tantalum (Ta) to be a suitable single-atom catalyst (SAC) for the nitrogen reduction reaction (NRR).

Dissociation probability of CH₄ dissociation on a surface depends on the symmetry of the minimum energy path, which in turn depends on the surface alloy compositions. The reaction path is symmetric, if the top layer is replaced by the guest metals.

Infrared multiple photon dissociation spectra of V⁺(H₂O)_n depend on experiment conditions, with strong kinetic shift effects for large clusters.

A scheme for representing globally accurate reactive potential energy surfaces by combining Gaussian process regression and neural networks is proposed.

Ultrafast spectroscopy and quantum dynamics simulations elucidate the ∼0.1 ps ultrafast proton transfer of photoionized aqueous phenol.

Exciton (de)localization dynamics in molecular dimers are analyzed using surface hopping and quantum dynamical calculations.

Quantum-chemically supported electric beam deflection and photodissociation spectroscopy reveal the shape evolution and optical absorption of small Sn clusters with focus on the rotational, vibrational, multiphoton and dissociation characteristics.

Irradiation-driven molecular dynamics simulations provide atomistic insights into the structure and morphology of metal deposits grown during the FEBID process.