Accurate ab initio spectroscopic and thermodynamic properties of BBrx and HBBrx „xÄ0, ¿1, À1..

The near-equilibrium potential energy functions ~PEFs! of BBr, its ions, BBr and BBr, and HBBr and its ions, HBBr and HBBr, have been determined using the singles and doubles coupled cluster method including a perturbational correction for connected triple excitations, CCSD~T!, together with systematic sequences of correlation consistent basis sets. A wide range of spectroscopic constants have been derived from the calculated PEFs as a function of basis set, including results obtained at the extrapolated complete basis set ~CBS! limit. After the explicit inclusion of relativistic and core–valence correlation effects, the agreement with the available experimental values is excellent at the CCSD~T!/CBS level of theory. Accurate predictions for the spectroscopic constants of the ions are made. The 0 K adiabatic ionization potentials and electron affinities are predicted to be ~in kcal/mol! 224.8, 4.3 ~BBr! and 172.8, 22.2 ~HBBr!. The 0 K proton affinity of BBr is calculated to be 203.7 kcal/mol, while DH f (0 K) of BBr and HBBr are predicted to be 62.3 and 51.1 kcal/mol, respectively. The dipole moments and infrared intensities of the ions are calculated to be relatively large, which should facilitate their characterization by experimental methods. © 2001 American Institute of Physics. @DOI: 10.1063/1.1405435#