Converged full-dimensional (6D) quantum mechanical calculation of energy levels of intramolecular stretching excited (HF)2(v1v 2) is presented for (v1v2) = (01), (10), (02), (20), and (11). The bound state calculation for the excited HF dimer employs the SQSBDE potential energy surface of Quack and Suhm and is for total angular momentum J = 0. This calculation provides the first rigorous theoretical result of energy levels for HF stretching excited HF dimer in full dimensions. The calculated fundamental transition frequencies are v1 = 3940.6 cm -1 and v2 = 3896.4 cm-1. These values are somewhat larger than the corresponding experimental measurement of 3930.9 cm-1 for v1 and 3868.3 cm-1 for v2. The overtone frequencies are calculated to be 2v1 = 7713.5 cm -1, 2v2 = 7642.5 cm-1, and v1 + v2 = 7841.8 cm-1. The theoretical tunneling splittings of the fundamentals v2 and v1 are, respectively, a factor of 5.3 and 3.7 smaller than the ground state splitting, compared to a factor of 3 from the experimental measurement. The splittings of the overtone states 2v 2, 2v1, and v1 + v2 are smaller than that of the ground state by factors of 9.6, 48, and 1.8, respectively. Some of the calculated energy levels of excited (HF)2 are spectroscopically characterized and assigned.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry