Efficient vibrationally correlated calculations using -mode expansion-based kinetic energy operators.

Due to its efficiency and flexibility, the -mode expansion is a frequently used tool for representing molecular potential energy surfaces in quantum chemical simulations. In this work, we investigate the performance of -mode expansion-based models of kinetic energy operators in general polyspherical coordinate systems. In particular, we assess the operators with respect to accuracy in vibrationally correlated calculations and their effect on potential energy surface construction with the adaptive density guided approach.

Theoretical modeling of molecules in weakly interacting environments: trifluoride anions in argon.

The properties of molecules can be affected by the presence of a host environment. Even in inert rare gas matrices such effects are observable, as for instance in matrix isolation spectroscopy. In this work we study the trifluoride anion in cryogenic argon environments.

The Peculiar Interaction of Trifluoride Anions with Cryogenic Rare Gas Matrices.

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.

A pair potential modeling study of F in neon matrices.

In this study, the structural and vibrational properties of a trifluoride anion trapped in solid neon are investigated. For that, a potential energy surface based on a truncated many-body expansion scheme is constructed from explicitly correlated coupled cluster calculations. Cluster modeling and minima hopping optimizations are used to evaluate different neon environments, revealing a dominant underlying structural motif in the guest-host system.

A Validation of Cluster Modeling in the Description of Matrix Isolation Spectroscopy.

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 molecule in an argon matrix were investigated with dispersion-corrected density functional theory calculations.