Rovibrational levels of helium hydride ion.

Dissociation energy (D(0)) of rovibrational levels of (4)HeH(+) has been predicted theoretically to the accuracy of the order of 0.01 cm(-1). The calculations take into account adiabatic and nonadiabatic corrections as well as relativistic and quantum electrodynamics effects. For the ground rovibrational level D(0) = 14,874.215(10) cm(-1) and it differs by several tens of the inverse centimeter from previous theoretical estimations. For a collection of about 50 transition energies measured between dipole connected levels the difference between theory and experiment is of the order of hundredths of cm(-1) or less.