Ro-vibrational coupling in high temperature thermochemistry of the BBr molecule.

High temperature thermochemistry of the BBr molecule is investigated with the classical approach in the temperature range of 300–20,000 K. The role of ro-vibrational coupling is elucidated. The internal partition function, thermal energy, heat capacity, and entropy are calculated at three levels of approximation, i.e. taking into account bound states on the ground state ( 1 Σ ), including also two excited states ( 3 Π and 1 Π ), and finally adding the resonance and scattering states. The influence of these approximations on studied quantities is investigated. The entropy is found to be the least sensitive to approximations in the ro-vibrational coupling and the heat capacity the most sensitive. [ABSTRACT FROM AUTHOR]