Dynamic dipole polarizability of HeH+

The recently introduced ''vibronic'' method of calculating dynamic dipole polarizabilities has been applied to HeH+. Because this molecule has a vibrational component to its polarizability, it is shown that special care has to be taken when the method is applied. The method has been modified and the calculations carried out more rigorously than before in order to avoid certain problems which were previously undetected. New and more accurate results are reported and these are compared with those that can be obtained by using the traditional clamped nucleus method