“…In TROVE, the primitive vibrational basis set is represented by a symmetrized product of six one-dimensional vibrational functions φn 1 (r ℓ 1 ), φn 2 (r ℓ 2 ), φn 3 (r ℓ 3 ), φn 4 (θ ℓ 1 ), φn 5 (θ ℓ 2 ), and φn 6 (τ ), where ni denotes the associated local mode vibrational quanta, {r ℓ 1 , r ℓ 2 , r ℓ 3 , θ ℓ 1 , θ ℓ 2 } are linearized versions (Yurchenko et al 2007;Bunker & Jensen 1998) of the coordinates {rCO, rCH 1 , rCH 2 , θOCH 1 , and θOCH 2 }, respectively, and τ is the dihedral angle between the OCH1 and OCH2 planes. The functions φn i (qi) are obtained by solving the corresponding 1D Schrödinger equation (Yurchenko et al 2007) for the vibrational motion associated with the corresponding coordinate qi ∈ {r ℓ 1 , r ℓ 2 , r ℓ 3 , θ ℓ 1 , θ ℓ 2 , τ }, with the other coordinates held fixed at their equilibrium values, where the Numerov-Cooley method (Noumerov 1924;Cooley 1961) is used. The direct product of the 1D basis functions is contracted using the polyad condition:…”