The effect of different molecular parameters on the temperature depend
ence of the adiabatic charge-dipole capture rate constant is examined.
Generally, such a rate constant depends on three dimensionless parame
ters. The relationship is so involved that two-parametric interpolatio
n formulae developed by Tree are not always valid. Tree's formulae wor
k perfectly well for the systems that feature large enough values for
the parameter xi. Most physically realistic ion-dipole captures belong
to this class. However, thermal electron-dipole captures feature smal
l xi; dynamics is, consequently, non-adiabatic, and the low-temperatur
e limit to the capture rate is not observed. Two-parametric interpolat
ion overestimates the exact value under such conditions. (C) 1997 Publ
ished by Elsevier Science B.V.