Revealing SO₂ and CO₂ adsorption features on forsterite <i>via</i> IR spectroscopy and automated computational approaches

The interaction between interstellar molecules and silicate dust plays a critical role in the chemical evolution of interstellar and circumstellar environments. In this work, we combine <i>in situ</i> infrared (IR) spectroscopy with automated density functional theory (DFT) calculations to investigate the adsorption and vibrational signatures of CO₂ and SO₂ on forsterite surfaces. Experimental IR spectra collected under cryogenic conditions reveal coverage- and temperature-dependent features that evolve from physisorbed to chemisorbed regimes. To interpret these observations, we construct theoretical spectra from a large ensemble of adsorption configurations across multiple surface terminations, weighted by their Boltzmann distributions at 100 K and by a per-surface abundance factor. The resulting spectra reproduce key experimental features, enabling the identification of binding trends. For CO₂, we predict the transition from weakly bound species to carbonate-like modes at lower frequencies. For SO₂, our simulations identify the dominant bands due to bidentate and tridentate chemisorption. This integrative approach highlights the importance of surface morphology and thermodynamic weighting in reconciling theory and experiments providing a framework for the spectroscopic analysis of molecular adsorption on interstellar dust analogs.