The barrier to linearity of hydrogen sulphide

High-quality ab initio quantum chemical methods, including higher-order cou pled cluster (CC) and many-body perturbation (MP) theory, as well as full c onfiguration interaction (FCI) benchmarks, with basis sets ranging from [S/ H] [4s3p1d/2s1p] to [9s8p7d5f4g3h2i/7s6p5d4f3g2h] have been employed to obt ain the best technically possible value for the barrier to linearity of hyd rogen sulphide. Following careful extrapolations of MP2, CCSD and CCSD(T) e nergies to the complete basis set (CBS) limit and inclusion of small correc tions due to scalar relativistic terms, core polarization and core correlat ion effects, and the diagonal Born-Oppenheimer correction (DBOC), the final electronic (vibrationless) extrapolated barrier height of this study is 24 423 +/- 75 cm(-1). (C) 2000 Elsevier Science B.V. All rights reserved.