Potentional Energy Function and Vertical Ionization Potential of BBrn（n=0，+1，+2）

Based on the atomic and molecular reaction statics，the ground electronic states i. e. BBr（X1Σ +），BBr+（X2Σ+）and BBr2+（X1Σ+）and the corresponding reasonable dissociative limits for these molecule and ions have been derived. Using the density functional method（B3LYP）and cc-pVDZ basis sets，the molecular equilibrium geometry and dissociation energy for BBr+（X2Σ+）and BBr2+（X1Σ+）have been calculated. The analytical potential energy functions of BBr and its ions BBr + and BBr2 + are correctly determined. The force fields and spectroscopic have been worked out from their analytical potential energy functions parameters of BBr+（X2Σ +）and BBr2+（X1Σ+）. The calculated results for Re，De，f2，f3，f4，Be，αe，ωe and ωexe are 0. 1766 nm，3. 531 eV，4. 88 aJ/cm2，-27.29 aJ/cm3，111. 03 aJ/cm4，0. 5677，0. 00477，932. 5 and 6. 057 cm-1 respectively for BBr+ and 0. 1726 nm，2. 452 eV，23. 711 aJ/cm2， -175. 61 aJ/cm3，611. 96 aJ/cm4，0. 5945，0. 001774，261. 079 and 1446. 2 cm-1 respectively for BBr+2，which are in agreement with experimental or calculated values in references. The vertical ionization potentials of BBr are I+=9. 583675 eV and I++=29. 34234 eV. It is indicated from calculation that there are the minimum points in the potential energy curves of BBr+ and BBr2+，so it can be decided that BBr，BBr+ and BBr2+ can be stable.