HeLi^n^+(n=0, 1)簇合物的稳定性和垂直激发态光谱

本文用ab initio研究了簇合物HeLi^n^+(n=0, 1)的几何构型和成键性质。在MP2(FULL)/6-31G**, 水平优化所得LeLi^+的平衡键长为0.2062nm, 与实验值0.205nm十分吻合。比较了HeLi^+(X^1∑^+和a^3∑^+), HeLi(X^2∑^+和a^4II)以及HLi(X^1∑^+)的稳定性, 计算了HeLi^+基态的相关能, 势能曲线和垂直激发态光谱。计算采用了6-31G**, 6-311G**,6-311G(2df, 2pd), 6-311G(3df, 2pd)和6-311+G(3df, 2pd)基组; 采用的方法包括MP2(FULL), MP4, MCSCF, MRSDCI, CCD和ST4CCD。计算表明, 同价HeLi^n^+中激发态的离解能均远比基态的大, 其中HeLi^+(a^3∑^+)的离解能最高(60.49kj/mol),说明激发态是稳定束缚态。HeLi^+基态比等电子体HLi分子基态的稳定性小得多。HeLi^+由A^1∑^+到B^1II的垂直跃迁(3σ→1π)振子强度较大而垂直跃迁能较小。

The stability and the vertical excited states of elemental cluster HeLi^n^+ (n=0, 1)

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.