The interactions of HF, H2O and NH3 with Br2 are investigated at the MP2（full）/ aug-cc-pVDZ level. It is found that two kinds of stable complexes, halogen-bonded and hydrogen-bonded complexes, exist between Br2 and HF and between Br2 and H2O. The interaction energy analysis and natural population analysis （NPA） are conducted to these two kinds of complexes, indicating the halogen-bonded complexes are more stable than the corresponding hydrogen-bonded ones, and the binding energies of the former increase in the order HFH2O for the latter.
