BH分子基态和激发态解析势能函数和光谱性质

Analytical potential energy functions and spectroscopic properties of the ground and excited states of BH molecule

运用多参考组态相互作用的方法和Dunning’s相关调和基函数并含扩散基的大基组aug-cc-pV5Z,获得了BH分子基态(X1Σ+)和6个电子激发态(a3П,A1П,B1Σ+,b3Σ+,b3Σ-,C′1Δ)的势能曲线.利用Murrel-Sorbie函数(MS)和最小二乘方法拟合得到解析势能函数,拟合误差很小,表明所得到的解析势能函数能够很好地再现BH分子中原子间的相互作用情况.利用得到的解析势能函数计算出的光谱常数与实验值符合很好,进一步确认了所得解析势能函数的可靠性和准确性.用MS函数拟合出了准确度高的B1Σ+态双势阱势能曲线解析表达式,拓展了MS函数的应用范围.

The potential energy curves（PECs）for the ground state（X1Σ＋）and six excited states（a3П,A1П,B1Σ＋,b3Σ-,c3Σ＋,and C 1Δ）of BH molecule have been computed using the multireference configuration interaction（MRCI）method and Dunning s correlation consistent basis sets aug-cc-pV5Z.By employing the Murrell-Sorbie function（MS）and the least-square fitting method,the analytical potential energy functions（APEFs）of these states are obtained.The root means square（RMS） errors between the fitted results and the ab initio values are very small in comparison with the chemical accuracy （349.755 cm-1）, which implies that the APEFs can well display the interactions between the two atoms of BH molecule. Based on the APEFs, we have calculated the spectroscopic parameters and compared them with the available theoretical and experimental values. The calculating results are in good agreement with the experimental values, which shows that the present APEFs are accurate. The double-well PEC for the B1∑ state has also been fitted accurately with MS function, which provides a sample for more wider application of MS function.