First-principles investigations of the trifluoride anion in a neon environment reveal a small blue-shift of the fundamental vibrational excitations.

Ab initio modeling of trifluoride anions in argon matrices shows that subtle environmental changes can affect the molecular vibrations in qualitatively differing ways.

Matrix isolation is a fundamental tool for the synthesis and characterization of highly reactive novel species and investigation of unusual bonding situations. Ab initio descriptions of guest-host interactions in matrix isolation are highly demanding, as the weak interactions between guest and host can influence the former's oftentimes challenging electronic structure. In this study, the matrix effects on a single CO 2 molecule in an argon matrix were investigated with dispersion-corrected density functional theory calculations. Three different guest-host structures were described by bulk models employing periodic boundary conditions as well as cluster models. The calculations were analyzed with respect to structural features of the CO 2 molecule and its immediate surroundings. Also, the molecule's harmonic frequencies were determined. The calculated frequencies were in qualitative agreement with experimental observations. The cluster models produced comparable results given that the clusters were large enough to reproduce the structural features of the bulk model.

In this contribution, we present theoretical modeling of the interaction between rare gas matrices and a trifluoride guest anion, as well as its quantitative effect on measured vibrational spectra. Using a combination of coupled-cluster electronic structure calculations and a many-body potential expansion coupled with permutation invariant polynomial fitting and anharmonic vibrational spectrum simulations, we shed light on the origin of the trifluoride matrix effects observed experimentally. The theoretical spectra are found to reproduce accurately the measured data while providing deeper insights into the effects of the guest–host interaction. The investigations reveal that neon can only stabilize trifluoride in hexagonal cavities formed by double vacancies, while argon can host the anion in a variety of cavities ranging from zero to two defects in the matrix. The origin of this structural variability can be traced back to the disparate strengths of the host–host interactions in neon and argon. The present work demonstrates the importance of theoretical modeling to complement matrix isolation experiments, which alone do not provide direct information about the structure of the matrices or about the physical origin of their interaction and of their spectroscopic signature.

No abstract