Spectroscopic properties under vibrational strong coupling in disordered matter from path-integral Monte Carlo simulations.

Vibrational strong coupling (VSC), the strong coupling between a Fabry-Perrot cavity and molecular vibrations at mid-infrared frequencies, has received important attention in the last years due to its capacity of modifying both vibrational spectra and chemical reactivity. VSC is a collective effect, and in this work, we introduce Path Integral Monte Carlo (PIMC) simulations that not only take into account the quantum character of the molecular vibrations and of the optical resonance of the cavity but also reproduce this collective behavior by considering multiple replicas of the molecular system. Moreover, we show that it is possible to extract from the PIMC simulations the decomposition of the hybrid optical and molecular states in terms of the bare molecular modes.

Extending Non-Perturbative Simulation Techniques for Open-Quantum Systems to Excited-State Proton Transfer and Ultrafast Non-Adiabatic Dynamics.

Excited state proton transfer is an ubiquitous phenomenon in biology and chemistry, spanning from the ultrafast reactions of photobases and acids to light-driven, enzymatic catalysis and photosynthesis. However, the simulation of such dynamics involves multiple challenges, since high-dimensional, out-of-equilibrium vibronic states play a crucial role, while a fully quantum description of the proton's dissipative, real-space dynamics is also required. In this work, we extend the powerful matrix product state approach to open quantum systems (TEDOPA) to study these demanding dynamics, and also more general nonadiabatic processes that can appear in complex photochemistry subject to strong laser driving.

Orientational Disorder Drives Site Disorder in Plastic Ammonia Hemihydrate.

In the 2-10 GPa pressure range, ammonia hemihydrate H_{2}O:(NH_{3})_{2} (AHH) is a molecular solid in which intermolecular interactions are ruled by distinct types of hydrogen bonds. Upon heating, the low-temperature ordered P2_{1}/c crystal (AHH-II) transits to a bcc phase (AHH-pbcc) where each site is randomly occupied by water or ammonia. In addition to the site disorder, experiments suggest that AHH-pbcc is a plastic solid, but the physical origin and mechanisms at play for the rotational and site disordering remain unknown.

On the composition and isomerism effect in the thermal and structural properties of choline chloride/hydroxyphenol deep eutectic solvents.

We have carried out a comparative study on three sets of eutectic mixtures based on choline chloride (ChCl) and hydroxyphenol isomers having two hydroxyl groups in the -, -, and -positions of the aromatic ring, namely catechol (Cate), resorcinol (Reso), and hydroquinone (Hydro), respectively. Differential scanning calorimetry highlighted a different thermal behavior of the mixtures depending on the composition and precursor isomerism. These systems behave as deep eutectic solvents (DESs) with the exception of the ChCl/Cate mixture at a 1 : 0.