The barrier to linearity of hydrogen sulphide

High-quality ab initio quantum chemical methods, including higher-order coupled cluster (CC) and many-body perturbation (MP) theory, as well as full configuration interaction (FCI) benchmarks, with basis sets ranging from [S/H] [4s3p1d/2s1p] to [9s8p7d5f4g3h2i/7s6p5d4f3g2h] have been employed to obtain the best technically possible value for the barrier to linearity of hydrogen sulphide. Following careful extrapolations of MP2, CCSD and CCSD(T) energies to the complete basis set (CBS) limit and inclusion of small corrections due to scalar relativistic terms, core polarization and core correlation effects, and the diagonal Born–Oppenheimer correction (DBOC), the final electronic (vibrationless) extrapolated barrier height of this study is 24 423±75 cm−1.