理论研究B_2分子X^3Σ_g^-和A^3Π_u态的光谱性质

Study on spectroscopic properties of B_2(X^3Σ_g^-,A^3Π_u) molecule

采用Davidson修正的内收缩多参考组态相互作用方法及Dunning等的相关一致基aug-cc-pV6Z计算了B_2分子X^3∑_g^-和A^3Π_u电子态的势能曲线.利用总能量外推公式,将两个电子态的总能量分别外推至完全基组极限.对势能曲线进行核价相关修正及相对论修正计算,得到了同时考虑两种效应修正的外推势能曲线.通过同位素质量识别,得到了主要的同位素分子^(11)B^(11)B和^(10)B^(11)B的X^3Σ_g^-和A^3Ⅱ_u电子态的光谱常数T_e,R_e,ω_e,ω_ex_e,ω_ey_e,B_e,β_e和γ_e.求解双原子分子核运动的径向Schr(o|¨)dinger方程,找到了无转动的同位素分子^(11)B_2(X^3Σ_g^-,A^3Π_u)和^(10)B^(11)B(X^3∑_g^-,A^3Π_u)的全部振动态.针对每一同位素分子的每一振动态,分别计算了其振动能级和惯性转动常数等分子常数,它们均与已有的实验结果较为一致.其中,^(10)B^(11)B(A~Π_u)分子的光谱常数和分子常数属首次报道.

The X3∑g-and A3Пu states of B2 molecule are studied using highly accurate valence internally contracted multireference configuration interaction approach including the Davidson modification. The Dunning＇s correlation-consistent basis sets, aug-cc-pV6Z and aug-cc-pV5Z, are used in the study. To obtain more reliable results, the potential energy curves （PECs） of two electronic states are extrapolated to the complete basis set limit by the two-point total-energy extrapolation scheme. The effects of the core-valence correlation and relativistic correction on PEC are taken into account. Employing these PECs, the spectroscopic parameters （Te, Re,we.wexe,weye,Be,αe,βe and γe） of the X3∑g- and A3Пu states of two main isotopes （11B2, l^BllB） are determined and compared with those reported in the literature. Comparison with the experimental data demonstrates that the present results are accurate. With the PECs determined here, the whole vibrational states for 11B2 （X3∑g-, A3Пu） and 10B11B （X3∑g-, A3Пu） are determined when the rotational quantum number J equals zero （J = 0） by numerically solving the radical Schrtdinger equation of nuclear motion. For each vibrational state of every isotope species, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental findings.