Accurate bond dissociation energies (D₀) for FHF⁻ isotopologues

Abstract

Accurate bond dissociation energies (D ₀) are determined for three isotopologues of the bifluoride ion (FHF⁻). While the zero-point vibrational contributions are taken from our previous work (P. Sebald, A. Bargholz, R. Oswald, C. Stein, P. Botschwina, J. Phys. Chem. A, DOI: 10.1021/jp3123677), the equilibrium dissociation energy (D _e ) of the reaction was obtained by a composite method including frozen-core (fc) CCSD(T) calculations with basis sets up to cardinal number n = 7 followed by extrapolation to the complete basis set limit. Smaller terms beyond fc-CCSD(T) cancel each other almost completely. The D ₀ values of FHF⁻, FDF⁻, and FTF⁻ are predicted to be 15,176, 15,191, and 15,198 cm⁻¹, respectively, with an uncertainty of ca. 15 cm⁻¹.

Keywords:

• bifluoride ion
• bond dissociation energy
• coupled cluster
• zero-point energy

Notes

^a Equilibrium bond lengths chosen are 0.9168 Å for HF [26] and 1.13961 Å for FHF⁻ [10].

^a Using auxiliary basis sets AVnZ/JKFIT, AVnZ/MP2FIT, and AVnZ/OPTRI [29–32] in conjunction with geminal parameters 1.2, 1.4, and 1.5 for n = T, Q, and 5, respectively. The underlying Hartree–Fock calculations include CABS singles in all cases.

^a Using ACVnZ basis sets.

^a CP corrected values in parentheses. Valence electrons are correlated.

^a Taken from Ref. [10]; the corrected PEF is employed.

^b Values from Ref. [43] in parentheses.

^c Values in parentheses from calculations with CCSD(T*)-F12b/AV5Z PEFs.