OpacityTool computes dust opacities for disc modelling; it includes a number of robust facts obtained from observations and theory and goes beyond astronomical silicates. It provides output files with κext(λ),κabs(λ),κsca(λ) as a function of wavelength λ, and the 6 scattering matrix elements for randomly oriented particles, F11(λ,θ), F12(λ,θ), F22(λ,θ), F33(λ, θ), F34(λ, θ), F44(λ, θ) as functions of wavelength and scattering angle θ.

This code is superseded by optool (ascl:2104.010).

Detailed studies of exoplanet and brown dwarf atmospheres rely on precise knowledge of the spectral features of possible atmospheric species. These features are a result of the interaction of different molecules and atoms with the radiation of the host star or the intrinsic thermal radiation of the object. The interaction is described by the opacity of a species, which determines how much light is absorbed at a given wavelength. The strength and shape of these opacities are very dependent on the temperature and pressure of the atmosphere, which is why they have to be calculated for a wide range of conditions. line racer is a Python package that enables computing high-resolution opacities from large molecular line lists in an effective manner. It offers users a wide range of options to customize opacity calculations to their needs and available hardware. The code is designed for efficient parallelization on multi-core and multi-node systems and can produce outputs compatible with popular atmospheric modeling and retrieval tools.

The 1D cloud model code ExoLyn solves the transport equation of cloud particles and vapor under cloud condensation rates that are self-consistently calculated from thermodynamics. It can be combined with optool (ascl:2104.010) to calculate solid opacities and with petitRADTRANS (ascl:2207.014) to generate transmission or emission spectra. The code balances physical consistency with computational efficiency, opening the possibility of joint retrieval of exoplanets' gas and cloud components. ExoLyn has been designed to study cloud formation across a variety of planets, such as hot Jupiters, sub-Neptunes, and self-luminous planets.

Optool computes dust opacities and scattering matrices, for specific grain sizes or averaged over size distributions. It is derived from OpacityTool (ascl:2104.009) and implements the Distribution of Hollow Spheres (DHS) statistical method to approximate irregular and low porosity grains. Mie theory is available as a limiting case of DHS. It also implements the Tazaki Modified Mean Field Theory (MMF) to treat fractal and highly porous aggregates. The refractive index data for many astronomically relevant materials are compiled into the code, and external refractive index data can be used as well. A compact and intuitive command line interface makes it easy to construct complex particles on the fly. Available output formats are ASCII and FITS, including files directly readable by RADMC-3D (ascl:1202.015). A python interface to the FORTRAN program is included.