A full dimensional potential for H2O2 (X1A) covering all dissociation channels

Abstract

This work presents a new full dimensional potential energy surface for the ground singlet state of hydrogen peroxide, H₂O₂. This potential is based on a 3 × 3 matrix to accurately reproduce all the different dissociation channels in accordance with the Wigner–Witmer rules, namely, O(¹D) + H₂O(X¹A₁), OH(X²Π) + OH(X²Π), O₂(a¹Δ_g) + H₂(X¹Σ_g⁺) e H(²S) + HO₂(X²A′′). It has been obtained by fitting more than 38 thousand ab initio energies computed using the aug-cc-pVTZ and aug-cc-pVQZ basis sets and extrapolated to the basis set limit. The functional form used to represent the four-body short-range interactions is based on a sum of polynomial functions of the fourth degree multiplied by a range factor, both built with intrinsic permutation symmetry and centred at specific reference geometries, to which the ab initio points computed are assigned based on a k-means algorithm. It also accounts for the electrostatic dipole–dipole interaction between two OH(²Π) fragments.