Structures and Spectroscopic Properties of Small Negative Molecular Ions — Theory and Experiment

Explicitly correlated coupled cluster theory at the CCSD(T*)-F12b level in conjunction with the aug-cc-pV5Z basis set has been used in the calculation of three-dimensional potential energy and dipole moment surfaces for the bifluoride ion (FHF(-)). An empirically corrected analytical potential energy function (PEF) was obtained by fit to four pieces of accurate spectroscopic information. That PEF was used in variational calculations of energies and wave functions for a variety of rovibrational states of the isotopologues FHF(-), FDF(-), and FTF(-). Excellent agreement with available data from IR laser diode spectroscopy is observed and many predictions are being made. Unusual isotope effects among the spectroscopic constants and unusual features of the calculated line spectra are discussed.

show abstract

Anharmonic vibrational frequencies and vibrationally averaged structures and nuclear magnetic resonance parameters of FHF−

Hirata

Yagi

Perera

et al. 2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

The anharmonic vibrational frequencies of FHF(-) were computed by the vibrational self-consistent-field, configuration-interaction, and second-order perturbation methods with a multiresolution composite potential energy surface generated by the electronic coupled-cluster method with various basis sets. Anharmonic vibrational averaging was performed for the bond length and nuclear magnetic resonance indirect spin-spin coupling constants, where the latter computed by the equation-of-motion coupled-cluster method. The calculations placed the vibrational frequencies at 580 (nu(1)), 1292 (nu(2)), 1313 (nu(3)), 1837 (nu(1) + nu(3)), and 1864 cm(-1) (nu(1) + nu(2)), the zero-point H-F bond length (r(0)) at 1.1539 A, the zero-point one-bond spin-spin coupling constant [(1)J(0)(HF)] at 124 Hz, and the bond dissociation energy (D(0)) at 43.3 kcal/mol. They agreed excellently with the corresponding experimental values: nu(1) = 583 cm(-1), nu(2) = 1286 cm(-1), nu(3) = 1331 cm(-1), nu(1) + nu(3) = 1849 cm(-1), nu(1) + nu(2) = 1858 cm(-1), r(0) = 1.1522 A, (1)J(0)(HF) = 124+/-3 Hz, and D(0) = 44.4+/-1.6 kcal/mol. The vibrationally averaged bond lengths matched closely the experimental values of five excited vibrational states, furnishing a highly dependable basis for correct band assignments. An adiabatic separation of high- (nu(3)) and low-frequency (nu(1)) stretching modes was examined and found to explain semiquantitatively the appearance of a nu(1) progression on nu(3). Our calculations predicted a value of 186 Hz for experimentally inaccessible (2)J(0)(FF).

show abstract

Structures and Spectroscopic Properties of Small Negative Molecular Ions — Theory and Experiment

Cited by 3 publications

References 36 publications

Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

FHF^–Isotopologues: Highly Anharmonic Hydrogen-Bonded Systems with Strong Coriolis Interaction

Anharmonic vibrational frequencies and vibrationally averaged structures and nuclear magnetic resonance parameters of FHF−

Contact Info

Product

Resources

About

Structures and Spectroscopic Properties of Small Negative Molecular Ions — Theory and Experiment

Cited by 3 publications

References 36 publications

Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

Ab Initio Anharmonic Vibrational Analyses of Non-Rigid Molecules

FHF–Isotopologues: Highly Anharmonic Hydrogen-Bonded Systems with Strong Coriolis Interaction

Anharmonic vibrational frequencies and vibrationally averaged structures and nuclear magnetic resonance parameters of FHF−

Contact Info

Product

Resources

About

FHF^–Isotopologues: Highly Anharmonic Hydrogen-Bonded Systems with Strong Coriolis Interaction