Wydział Chemii

Małgorzata Biczysko

Riccardo Tarroni

Stuart Carter

2003

Journal of Chemical Physics

119

4197-4203

10.1063/1.1594174

Naukowa

Angielski

Artykuł

A theoretical study of the HBN radical in the X ²Π and A ²Σ+ states, taking into account vibronic coupling effects, is reported. The lowest (1²A',1²A'',2 ²A') potential energy surfaces (PES) of the HBN–BNH system have been studied to identify all stationary points. The HBN minimum was found to be 20.0 kcal/mol above BNH, with an isomerization barrier of ≈11 000 cm^–1 on the 1²A' surface. For the HBN isomer, accurate near-equilibrium three-dimensional diabatic PESs for the ground
X ²Π (1²A',1² A'') and first excited A ²Σ +(2 ²A') electronic states have been calculated at the multireference configuration interaction level of theory, with extended basis set. A vibronic coupling between bend and BN stretch, analogous to that found in the isoelectronic C₂H and HCN⁺ radicals, has been found to take place due to the crossing of the X ²Π and A ²Σ+ states at energies close to 11 000 cm^–1 . Vibronic energy levels of HBN and DBN have been calculated variationally using a previously developed method [Carter et al., Mol. Phys. 98, 1967 (2000)] suitable for three-atomic molecules showing three-state vibronic interactions. Energy levels of Σ and Π symmetry up to 10 000 cm^–1 for HBN, and 8800 cm^–1 for DBN, are reported. It is shown that due to the high-energy surface crossing, the vibronic interaction becomes non-negligible only for levels above 8500 cm^–1 . For all levels, Renner–Teller effects and Fermi resonances are analyzed.

http://dx.doi.org/10.1063/1.1594174

https://www.aip.org/