A harmonic force field for the mixed alkali halide dimer LiNaF2 is reported based on microwave centrifugal distortion coefficients and matrix-isolation vibrational frequencies for both 6LiNaF2 and 7LiNaF2, and an ab initio force field. It is compared to RHF and MP2 ab initio calculations, with a particular emphasis on determining reliable general alkali halide mean amplitudes of vibration l. Detailed comparisons between ionic model, RHF, MP2, and CCSD ab initio dipole moment values and the experimental value of 2.64(2) D are also made
