Effect of the Coriolis interaction on the average nuclear separation in nonlinear XY2 molecules

The average nuclear separations are calculated for XY2 molecules by means of the total vibrational-rotational wave function obtained by a method different from that developed by Nielsen and Amat. A small dimensionless parameter is introduced for an order-of-magnitude estimate of the vibrational-rotational interaction. Terms due to the Coriolis interaction are singled out.