Restricted-geometry quantum models beyond atoms: Application of the Eckhardt-Sacha approach to nonsequential double ionization in diatomic systems

We present a (1+1)-dimensional quantum model designed to describe nonsequential double ionization (NSDI) in homonuclear diatomic molecules exposed to strong linearly polarized laser fields. Extending the restricted-geometry framework previously developed for atomic systems by Eckhardt and Sacha, our approach captures key features of NSDI, including the characteristic knee structure in double ionization yields. Despite its simplifying assumptions, the model shows good agreement with experimental data and proves particularly suitable for systems with $σ$-type orbital symmetry. It offers a computationally efficient tool for exploring multi-electron dynamics in molecular systems.