(color online) Comparisons of (a)–(c) spectra, (d)–(f) ellipticity, and (g)–(i) relevant dipoles of odd harmonics for 3D model HeH²⁺ with I_p = 1.1 a.u., Z₁/Z₂ = 1.5, and R = 1.5 a.u. at θ = 10° (the left column), θ = 30° (middle), and θ = 50° (right). The odd spectra are calculated using Eq. (1) (accurate spectra, solid-black) and Eq. (2) (spectra associated with the transition of the electron back to only the ground state, dashed-red) with short-trajectory 3D TDSE simulations. The odd dipoles are calculated using Eq. (4) (previous dipoles, solid-black) and Eq. (6) (improved dipoles, dashed-red). The log₁₀ scale is used to show the spectra and dipoles.