PI: Sergey Yurchenko
Our 2025 programme delivered a coordinated set of spectroscopic and photochemical data products that directly enable robust interpretation of exoplanet and planetary atmospheres, especially for retrieval frameworks and for high-resolution cross-correlation spectroscopy (HRCCS). The work is united by a single technical requirement: extremely large, high-accuracy molecular datasets (line lists, empirical energies, pressure broadening, and photodissociation cross sections) that are computationally demanding to generate, validate, and package for community use. DiRAC HPC resources were essential for (i) large-scale variational nuclear-motion calculations, (ii) extensive continuum/photodissociation modelling across temperatures and wavelengths, (iii) high-throughput semi-classical line-shape calculations over broad perturber/temperature grids, and (iv) data conditioning steps needed to make these products “retrieval-ready” (replacement with empirical energies where available, consistent quantum assignments, and export into formats used by atmospheric codes). Among the highlights of this year work are the following publications.
Field-level synthesis for HRCCS: data needs and best practice (Nature Reviews Physics). We provided a community-facing synthesis of the data challenges and prospects for high-resolution exoplanet spectroscopy, emphasising how laboratory accuracy, completeness, and statistical practice control detection reliability and the shift from single-species detections toward whole-atmosphere characterisation.
CO₂: 12-isotopologue rovibrational line lists (MNRAS). We produced extensive rovibrational line lists for twelve CO₂ isotopologues, combining high-level variational modelling with accuracy improvements via replacement with empirical energy levels where available. The dataset supports isotopologue-resolved studies and terrestrial-abundance mixtures, and is designed for direct use in atmospheric opacity generation and retrieval workflows.
Photodissociation CH (MNRAS) and NH (J. Chem. Phys.). We computed temperature-dependent photodissociation cross sections for CH and NH, explicitly treating multiple electronic states and key physical pathways (including predissociation processes and tunnelling effects). The resulting cross sections support photochemical rate calculations in irradiated atmospheres and astrochemical environments.
C₂H₂ line broadening and shifts with key perturbers (JQSRT). We produced a comprehensive semi-classical dataset of pressure-broadening and shift coefficients for acetylene with major, constrained by extensive experimental data and extended across a broad temperature range. These parameters enable realistic line shapes required for forward models and retrievals in diverse conditions expected for exoplanetary atmospheres.