• Inverse R2: This descriptor is defined as the inverse of the R2 ( 1 𝑅 𝑖𝑗 ⁄ ) distance matrix, similar to the Coulomb matrix descriptor. • Delta R2: This descriptor represents the difference between the R2 vector of the current geometry at time t and the corresponding R2 vector of a reference geometry, typically the ground-state geometry (𝑅 𝑖𝑗 (𝑡) -𝑅 𝑖𝑗 (𝑟𝑒𝑓)).