Rovibrational energies of B2H2() from an explicitly correlated potential energy surface

The six-dimensional potential energy surface of the X ∼ 3 Σ g - electronic ground state of B2H2 was determined using spin-unrestricted explicitly correlated coupled cluster methodology. The analytic representation of this surface was used to compute the rovibrational energies of this boron hydride dimer. For the 11B2H2 species, the antisymmetric B–H stretching frequency is computed at 2693.2 cm−1, and an isotopic shift of +10.7 cm−1 is deduced for 10B2H2. Comparisons with the electronic ground state of diatomic fragments B2 and BH are discussed. The J = 1 ← 0 rotational transition is calculated at 50511.5 MHz for 11B2H2 and at 53551.0 MHz for 10B2H2. Spectroscopic constants of the deuterated isotopologues are reported.