单氘代氨NH $_2$ D与H $_2$的碰撞激发
Collisional excitation of singly deuterated ammonia NH$_2$D by H$_2$
摘要：
与H $_2$的碰撞速率系数的可用性是解释其能级在非局部化学平衡条件下填充的分子的观测的先决条件。在目前的研究中，我们提出的碰撞速率系数的NH $_2$ D / para-H $_2$（$J_2 = 0,2$）碰撞系统，能量水平高达$J_τ= 7_7$（$E_u$ $\sim$ 735 K）和气体温度范围内的$T = 5-300$ K。在低能和高能时，我们采用耦合态近似（CS），得到了基本上精确的紧耦合（CC）截面。对于高达$J_τ= 4_2$（$E_u$ $\sim$ 215 K）的能级，通过CS形式主义获得的截面根据几个CC参考点进行缩放。这些参考点随后用于估计更高水平的速率系数的准确性，这主要是由使用CS形式主义的限制。考虑到当前的势能面，速率系数，因此预计是准确的，在5%以内的水平低于$J_τ= 4_2$，而我们估计的精度为30%的水平更高。
英文摘要：
The availability of collisional rate coefficients with H$_2$ is a pre-requisite for interpretation of observations of molecules whose energy levels are populated under non local thermodynamical equilibrium conditions. In the current study, we present collisional rate coefficients for the NH$_2$D / para--H$_2$($J_2 = 0,2$) collisional system, for energy levels up to $J_τ= 7_7$ ($E_u$$\sim$735 K) and for gas temperatures in the range $T = 5-300$K. The cross sections are obtained using the essentially exact close--coupling (CC) formalism at low energy and at the highest energies, we used the coupled--states (CS) approximation. For the energy levels up to $J_τ= 4_2$ ($E_u$$\sim$215 K), the cross sections obtained through the CS formalism are scaled according to a few CC reference points. These reference points are subsequently used to estimate the accuracy of the rate coefficients for higher levels, which is mainly limited by the use of the CS formalism. Considering the current potential energy surface, the rate coefficients are thus expected to be accurate to within 5\% for the levels below $J_τ= 4_2$, while we estimate an accuracy of 30\% for higher levels.
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