From the electronic structure point of view, second-order multiconfigurational perturbation theory applied to reference wavefunction (CASPT2), generated at the Complete Active Space Space Self-Consistent Field (CASSCF), has been shown to push the limit of the accuracy with a computational cost still affordable to obtain accurate dynamics in the ultrafast time scale for relatively small chromophores. The computational bottleneck is given by the choice of the active space (AS) and its size, which influences the accuracy of the calculation; alas often the Sword of Damocles is on the computational feasibility of nonadiabatic simulations using such a method to calculate electronic energies on-the-fly at each time step. However, the continuous developments of the community have been partially overcoming some of the limitations to the applicability of CASPT2 in dynamics. In particular, the recently introduced analytical gradients 47-51 and extended multi-state variation of CASPT2, specifically developed to deal with strongly correlated wavefunctions, have now made simulations possible that were previously fantastical. One of the main software to run and advance multiconfigurational perturbation theory is, without doubt, OpenMolcas, due to its extensive and continued implementation made by its community, its accuracy, reliability and its being fully open-source. However, although AIMS and CASPT2 lie among the highest standards in terms of accuracy/cost ratio, no software including the AIMS algorithm is currently interfaced with OpenMolcas to exploit all its potential, and all the CASPT2 flavors implemented, to propagate AIMS nonadiabatic dynamics. This work fills this gap and introduces a new interface between PySpawn and OpenMolcas to run AIMS nonadiabatic dynamics at the state-of-the-art CASSCF//CASPT2 level. One of the main strengths of this interface is offering an open-source implementation of AIMS with a high level of accuracy in the calculations of electronic energies. The interface allows the exploitation of all the already existing implementations inside OpenMolcas, including the recently introduced CASPT2 analytical gradients, which represents a notable speed-up in the excited states dynamics simulation at such a level of theory. However, the interface was designed flexibly so it will be easy to include all the future features that will be introduced in OpenMolcas by its broad, and constantly active community. In the following sections, we will first revise the PySpawn algorithm and structure, to offer a full overview of how the software propagates the nuclear wavefunction. Then, we will introduce the main characteristic of the interface and we will finally show an exemplary application. Thanks to our interface we could test the effect of different and recent CASPT2 implementations in the nonadiabatic dynamics of fulvene following the excitation to S 1 , comparing with the well-known CASSCF one. These capabilities make the following implementation unique in the current plethora of software for nonadiabatic dynamics. This represents an important step towards a wider application of AIMS-based nonadiabatic dynamics combined with high-accuracy excited states calculations.