A scaling law for angular distributions for chemical reactions

The direct interaction with product repulsion model reproduces many features of reactions such as O + H2 → OH + H at high collision energy. The model predicts that the differential cross section I(θ) sin θ depends only on the reduced energy Eθ = (cot2β)E, where E is the relative energy, cot2β is a mass factor, and β is the skew angle. In this Letter we test this scaling law for O + H2 → OH + H and O + HD → OH + D and OD + H using the quasiclassical trajectory method on a reasonable potential energy surface. The scaling law works well.