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

The all-electron CCSD(T)/cc-pCVTZ level of theory was used to generate a 63 point discrete potential energy hypersurface for the chi (2)A(1) electronic state of He2C3+. The optimized geometry was of C-2v symmetry with a RC-He bond length of 1.218 Angstrom and an included bond angle of 107.9 degrees. 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 ab initio surface yielded a (chi(2))(1/2) value of 1.35 x 10(-5) E-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.