Penning spectroscopy and structure of acetylene oligomers in He nanodroplets

Penning spectroscopy of acetylene molecules dissolved in superfluid He nanodroplets reveals the loosely held molecular aggregate collapsing into a covalently bound oligomer ion upon indirect ionization effected by the photoexcited He* in the host.

Fromage: A Library for the Study of Molecular Crystal Excited States at the Aggregate Scale

<p>The study of photoexcitations in molecular aggregates faces the twofold problem of the increased computational cost associated with excited states and the complexity of the interactions among the constituent monomers. A mechanistic investigation of these processes requires the analysis of the intermolecular interactions, the effect of the environment, and 3D arrangements or crystal packing on the excited states. A considerable number of techniques have been tailored to navigate these obstacles, however they are usually restricted to in-house codes and thus require a disproportionate effort to adopt by researchers approaching the field. Herein we present the FRamewOrk for Molecular AGgregate Excitations (fromage), which implements a collection of such techniques in a Python library complemented with ready-to-use scripts. The program structure is presented and the principal features available to the user are described: geometrical analysis, exciton characterisation and a variety of ONIOM schemes. Each is illustrated by examples of diverse organic molecules in condensed phase settings. The program is available at https://github.com/Crespo-Otero-group/fromage.</p>