A comprehensive experimental and theoretical study of H2-CO spectra
A comprehensive experimental and theoretical study of H2-CO spectra
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DOI：
10.1063/1.4791712
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发表时间：
2013-02-28
影响因子：
4.4
通讯作者：
Szalewicz, Krzysztof
中科院分区：
文献类型：
--
作者：
Jankowski, Piotr;Surin, L. A.;Szalewicz, Krzysztof
详细描述了在六维网格上计算的 H-2-CO 复合物的新从头算相互作用势能表面（即，包括对 H-H 和 C-O 分离的依赖性）。首先使用具有单次、双次和非迭代三重激发和大基组的耦合簇方法计算相互作用能，然后进行外推程序。接下来，通过较小基组的计算添加迭代三重和非迭代四重激励的贡献。然后将所得的相互作用能分别在 H-2 和 CO 的基态以及基态和第一激发态振动波函数上进行平均。所得的两个四维势能表面通过解析表达式进行拟合。从这些表面计算出的理论红外光谱已被显示[P. Jankowski, A. R. W. McKellar 和 K. Szalewicz, Science 336, 1147 (2012)] 与对位和邻位 H(2)-CO 配合物的实验光谱在波数的百分之几内非常一致。在后一种情况下，该协议使得在测量十年后对实验光谱进行分配成为可能。在本文中，我们提供了有关表面发展和谱线分配过程的详细信息。此外，我们还为 paraH(2)-CO 指定了一些之前未指定的跃迁。目前工作的一个全新内容是使用微波光谱法对邻H(2)-CO 配合物进行实验研究。通过与红外实验（包括新的低温实验）和理论光谱的比较，对测量光谱的大部分进行了解释。更好地了解对位和邻位 H(2)-CO 配合物的光谱，为在空间中重新搜索结合的 H-2-CO 配合物奠定了坚实的基础。 (C) 2013 年美国物理研究所。 [http://dx.doi.org/10.1063/1.4791712]
A detailed description of a new ab initio interaction potential energy surfaces for the H-2-CO complex computed on a six-dimensional grid (i.e., including the dependence on the H-H and C-O separations) is presented. The interaction energies were first calculated using the coupled-cluster method with single, double, and noniterative triple excitations and large basis sets, followed by an extrapolation procedure. Next, a contribution from iterative triple and noniterative quadruple excitations was added from calculations in smaller basis sets. The resulting interaction energies were then averaged over the ground-state and both ground-and first-excited-states vibrational wave functions of H-2 and CO, respectively. The two resulting four-dimensional potential energy surfaces were fitted by analytic expressions. Theoretical infrared spectra calculated from these surfaces have already been shown [P. Jankowski, A. R. W. McKellar, and K. Szalewicz, Science 336, 1147 (2012)] to agree extremely well, to within a few hundredth of wavenumber, with the experimental spectra of the para and orthoH(2)-CO complex. In the latter case, this agreement enabled an assignment of the experimental spectrum, ten years after it had been measured. In the present paper, we provide details concerning the development of the surfaces and the process of spectral line assignment. Furthermore, we assign some transitions for paraH(2)-CO that have not been assigned earlier. A completely new element of the present work are experimental investigations of the orthoH(2)-CO complex using microwave spectroscopy. Vast parts of the measured spectrum have been interpreted by comparisons with the infrared experiments, including new low-temperature ones, and theoretical spectrum. Better understanding of the spectra of both para and orthoH(2)-CO complexes provides a solid foundation for a new search of the bound H-2-CO complex in space. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4791712]