基态O和D原子的低能弹性碰撞及OD(X^2Π)自由基的准确解析势与分子常数

Elastic collisions between O and D atoms at low temperature and accurate analytic potential energy function and molecular constants of the OD (X^2Π) radical

利用CCSD(T)理论及相关一致五重基aug-cc-pV5Z构建了OD(X2Π)自由基的相互作用势,计算了这个自由基的光谱常数D0,De,Re,ωe,ωeχe及Be,其值分别为4.4574,4.6225eV,0.09702nm,2724.923,45.3534和10.0096cm-1,均与实验结果相符很好.利用这一相互作用势,在绝热近似下通过数值求解双原子分子核运动的径向薛定谔方程,找到了J=0时OD(X2Π)自由基存在的全部23个振动态,完整地求出了每一振动态的振动能级、振动经典转折点、惯性转动常数和离心畸变常数,其值与实验结果相当一致.在1.0×10-11—1.0×10-3a.u.的能量范围内研究了基态O和D原子沿OD(X2Π)势能曲线的弹性碰撞,计算了这一碰撞的总截面和各分波截面,分析了各分波截面对总截面的不同贡献.结果表明:总截面的形状主要由s分波截面决定,尽管直到l=12的其他分波截面均有形状共振存在,但由于其强度较弱,大都湮没在较强的s分波截面中.

Interaction potential of the OD（X2^Π）radical is constructed by employing the CCSD（T）theory in combination with the correlation-consistent quintuple basis set,aug-cc-pV5Z,in the valence range.Using the potential,the spectroscopic parameters are accurately determined.The present D0,De,Re,ωe,ωeχe and Be values are of 4.4574,4.6225 eV,0.09702nm,2724.923,45.3534 and 10.0096 cm-1,respectively,which are in excellent agreement with the recent measurements wherever available.A total of 23 vibrational states have been found when J = 0 by solving the radial Schrdinger equation of nuclear motion.The complete vibrational levels,classical turning points,initial rotation and centrifugal distortion constants when J = 0 are reported for the first time,which are in good agreement with the available experimental results.The total and various partial-wave cross sections are calculated for the elastic collisions of O and D atoms in their ground states at low and ultralow temperatures when the two atoms approach each other along the OD（X2^Π）potential energy curve.The impact energy range covers a vange from 1.0×10^-11 to 1.0 ×10^-3a.u..One shape resonance has been found in the total elastic cross sections.Contribution to the total elastic cross sections by each partial wave is investigated carefully.The results show that the shape of the total elastic cross sections is mainly dominated by the s partial wave.The shape resonances coming from the higher partial waves are covered up by the strong s partial wave cross sections.