Rapid and predictive planet population synthesis model (RAPPS). I. Upgraded model and resulting synthetic populations

Exoplanet surveys have revealed a large diversity of planetary systems. Explaining the origin of such diversity requires integrated models of planet formation. Planet population synthesis (PPS) modelling is a key tool for linking theories with the statistical properties of observed exoplanets. In the upcoming decade, the number of known exoplanets is expected to increase ten-fold, and the range of planetary parameters will expand significantly due to near-future missions such as , PLATO, and Ariel. Roman We aim to develop a new PPS model capable of predicting planetary masses, radii, orbits, and atmospheric properties across a wide range of stellar hosts. Given the expected significant increase in observed planetary data, the model must also achieve a sufficiently high computational efficiency to allow a large number of simulations that can be statistically compared with observational results. In this study, we build upon our previous PPS model, which introduced the effects of water enrichment of primordial atmospheres through magma–atmosphere interactions, enhancing it to include a semi-analytical model for dynamical evolution of multiple-planet systems after disc dispersal; the model was demonstrated to reproduce the results of direct N-body simulations. Additional updates include revised prescriptions for disc gas evolution, resonance trapping, and atmospheric escape. We show that our updated model produces planetary distributions that differ from our previous results, particularly in the abundance of Earth-mass and sub-Earth-mass planets. These differences arise mainly from the new dynamical evolution treatment, and the resulting distributions are more consistent with other formation simulations using direct N-body integrations. Our simulations also demonstrate that enrichment of primordial atmospheres through magma–atmosphere interaction strongly influences both the occurrence of gas giants and the radius distribution of close-in super-Earths and sub-Neptunes. The upgraded PPS model provides a computationally efficient and physically comprehensive framework for predicting planetary properties across diverse stellar types. It enables large parameter surveys and robust statistical comparisons with observational data, thereby offering the foundation for future detailed studies and for model validation against exoplanet observations.