Rovibrational states and vibrational intensities of the χ 2A1 state of He2C3+

Abstract

The all-electron CCSD(T)/cc-pCVTZ level of theory was used to generate a 63 point discrete potential energy hypersurface for the χ ²A₁ electronic state of He₂C³⁺. The optimized geometry was of C_2v symmetry with a R_C–He bond length of 1.218 Åand an included bond angle of 107.9°. Dissociation products were also examined. A Pade′ (4,5) potential function, employing a Simons–Parr–Finlan expansion variable, was used in subsequent calculations. The fit to the discrete abinitio surface yielded a (χ²)^1/2 value of 1.35×10^-5E_h. The potential function was embedded in an Eckart–Watson rovibrational Hamiltonian, which was solved variationally. The "‘full’' anharmonic fundamental frequencies for the breathe, bend and asymmetric stretch vibrations were 1199.2, 673.4 and 1411.9 cm^-1 respectively. Vibrational intensities were calculated using the variational wavefunctions and a dipole moment function generated from an all-electron QCISD/aug-cc-pVTZ 43 point dipole moment surface.