Efficient simulations of interstellar gas-grain chemistry using moment equations
Efficient simulations of interstellar gas-grain chemistry using moment equations
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DOI：
10.1086/513421
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发表时间：
2007-03-20
影响因子：
4.9
通讯作者：
Biham, Ofer
中科院分区：
文献类型：
--
作者：
Barzel, Baruch;Biham, Ofer
尘埃颗粒表面的反应网络在星际云的化学中起着至关重要的作用，导致在弥漫的云中形成分子氢，以及在密集的分子云中形成各种有机分子。由于颗粒的亚微米尺寸和低通量，每个颗粒的反应物种数量可能非常小并且波动很大。在这些条件下，速率方程失效，表面反应网络的模拟需要随机方法，如主方程。然而，对于复杂网络，主方程变得不可行，因为方程的数量呈指数增长。本文介绍了一种基于矩方程的小颗粒反应网络模拟方法。方程的数量减少到每个反应物种只有一个方程，每个反应只有一个方程。然而，该方法提供了准确的结果，这是在良好的协议与主方程。该方法被证明是最近被证明是至关重要的甲醇网络。
Networks of reactions on dust-grain surfaces play a crucial role in the chemistry of interstellar clouds, leading to the formation of molecular hydrogen in diffuse clouds as well as various organic molecules in dense molecular clouds. Due to the submicron size of the grains and the low flux, the population of reactive species per grain may be very small and strongly fluctuating. Under these conditions rate equations fail, and the simulation of surface-reaction networks requires stochastic methods such as the master equation. However, the master equation becomes infeasible for complex networks because the number of equations proliferates exponentially. Here we introduce a method based on moment equations for the simulation of reaction networks on small grains. The number of equations is reduced to just one equation per reactive species and one equation per reaction. Nevertheless, the method provides accurate results, which are in excellent agreement with the master equation. The method is demonstrated for the methanol network that has been recently shown to be of crucial importance.