The equilibrium geometric structures of the elemental clusters HeLi^n^+ (n=0, 1) have been opttimized by using ab initio and analytic energy gradients at the MP2(FULL)/6-31G** level. The stabilities were studied for HeLI (X^2∑^+), HeLi(a^4II), HeLi(X^1∑^+) and HeLi^+ (a^3∑^+). The correlative energies and potential curves of the ground state (X^1∑^+) of HeLi^+ were also calculated using the 6-311G**, 6-311G(2df, 2pd), 6-311G(3df, 2pd) and 6-311+G(3df, 2pd) standard basis sets with the MP2(FULL), MP4, MCSCF, MRSDCI, CCD and ST4CCD methods. In addition, vertical excited energies and oscillator strengths of the electronic state (X^1∑^+) for HeLi^+ were obtained from the MCSCF method. The results show that the stability of HeLi^+ (X^1∑^+) and HeLi^+ (a^3∑ ^+) is higher than that of HeLi(X^2∑^+) and HeLi(a^4II) respectively. Between HeLi^+ (X^1∑^+) and HLi (X^1∑^+), the stability of the latter was higher than the former. For HeLi^+ (X^1∑^+), the transition from A^1∑^+ state to B^1II state (3σ→1π) has larger oscillator values and smaller vertical transition energy.

Key words: STABILITY, EXCITED STATE, AB INITIO CALCULATION