A variational calculation of vibrational levels of vinyl radical.

We report the vibrational energy levels of vinyl radical (VR) that are computed with a Lanczos eigensolver and a contracted basis. Many of the levels of the two previous VR variational calculations differ significantly and differ also from those reported in this paper. We identify the source of and correct symmetry errors on the potential energy surfaces used in the previous calculations. VR has two equivalent equilibrium structures. By plotting wavefunction cuts, we show that two tunneling paths play an important role. Using the computed wavefunctions, it is possible to assign many states and thereby to determine tunneling splittings that are compared with their experimental counterparts. Our computed red shift of the hot band at 2897.23 cm⁻¹, observed by Dong et al. [J Chem. Phys. 128, 044305 (2008)], is 4.47 cm⁻¹, which is close to the experimental value of 4.63 cm⁻¹. [ABSTRACT FROM AUTHOR]