e sCI method implemented in P is based on the CIPSI (Con guration Interaction using a Perturbative Selection made Iteratively) algorithm which complements the variational sCI energy with a PT2 correction. Additional external plugins have been recently added to perform calculations with multireference coupled cluster theory and range-separated density-functional theory. All the programs are developed with the IRPF90 code generator, which simpli es collaborative work and the development of new features. P strives to allow easy implementation and experimentation of new methods, while making parallel computation as simple and e cient as possible on modern supercomputer architectures. Currently, the code enables, routinely, to realize runs on roughly 2 000 CPU cores, with tens of millions of determinants in the reference space. Moreover, we have been able to push up to 12 288 cores in order to test its parallel e ciency. In the present manuscript, we also introduce some key new developments: i) a renormalized second-order perturbative correction for e cient extrapolation to the full CI limit, and ii) a stochastic version of the CIPSI selection performed simultaneously to the PT2 calculation at no extra cost.