Potential energy surfaces and properties of the Br–HBr complex

Abstract

Semiempirical potential energy surfaces for Br–HBr are constructed, based on empirical Kr–HBr, Kr–Br and Kr–Kr potentials. The electrostatic forces due to the interaction of the quadrupole of the Br atom with the multipoles of the HBr molecule are included, and make a substantial contribution to the well depths. The potentials are presented in diabatic and adiabatic representations, with and without spin–orbit coupling. When spin–orbit coupling is included, the adiabatic well depth is 342 cm⁻¹, at a linear Br–H–Br configuration. Fully coupled bound-state calculations are carried out, and the ground state is found to be bound by 269 cm⁻¹. If the complex can be observed spectroscopically, it will provide a sensitive probe of the potential energy surfaces in the entrance and exit valleys of the Br+HBr reaction. In addition, the complex is likely to be important as a product of photodissociation of HBr in HBr dimer.