Felker Peter M, Bačić Zlatko
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States.
Department of Chemistry, New York University, New York, New York 10003, United States.
J Phys Chem A. 2021 Feb 4;125(4):980-989. doi: 10.1021/acs.jpca.0c10320. Epub 2021 Jan 21.
We report full-dimensional and fully coupled quantum bound-state calculations of the = 0, 1 intra- and intermolecular rovibrational states of the isotopically asymmetric HDO-CO complex. They are performed on the nine-dimensional (9D) potential energy surface (PES) [Liu, Y.; Li, J. 2019, 21, 24101]. The present study complements our earlier theoretical investigation of the 9D rovibrational level structure of the HO-CO and DO-CO complexes [Felker, P. M.; Bačić, Z. 2020, 153, 074107]. What distinguishes HDO-CO is that, unlike the two isotopically symmetric isotopologues, it does not display hydrogen-interchange tunneling but has two distinct isomers, the lower-energy D-bonded HOD-CO and the higher-energy H-bonded DOH-CO. The highly efficient methodology employed in the present calculations derives from our earlier study referenced above, taking into account the lower symmetry of HDO-CO. The full 9D rovibrational Hamiltonian is partitioned into three reduced-dimension Hamiltonians: the 5D rigid-monomer intermolecular vibrational Hamiltonian and two intramolecular vibrational Hamiltonians, one for the HDO monomer (3D) and another for the CO monomer (1D), and a 9D remainder term. The reduced-dimension Hamiltonians are diagonalized separately, and small portions of their low-energy eigenstates are incorporated in the compact final 9D product contracted basis covering all internal, intra- and intermolecular degrees of freedom of the complex. The 9D rovibrational Hamiltonian is diagonalized in this fully contracted basis. The calculations show that the eigenstates belonging to the D-bonded and H-bonded isomers, designated as and , respectively, are easy to identify, owing to the near-complete localization of their wave functions in either of the two minima on the PES. The computed intramolecular vibrational frequencies of the two monomers are either blue- or red-shifted, depending on the mode. The excitations of the intramolecular vibrational modes affect the energies of the low-lying and intermolecular vibrational states in the respective intramolecular manifolds. Comparison is made with the experimental data available in the literature.
我们报告了同位素不对称的HDO-CO络合物的(J = 0, 1)分子内和分子间振转态的全维全耦合量子束缚态计算。这些计算是在九维（9D）势能面（PES）上进行的[Liu, Y.; Li, J. 2019, 21, 24101]。本研究补充了我们早期对HO-CO和DO-CO络合物9D振转能级结构的理论研究[Felker, P. M.; Bačić, Z. 2020, 153, 074107]。HDO-CO的独特之处在于，与两种同位素对称的同位素异构体不同，它不显示氢交换隧穿，而是有两种不同的异构体，能量较低的D键合HOD-CO和能量较高的H键合DOH-CO。本计算中采用的高效方法源自我们上面引用的早期研究，并考虑了HDO-CO较低的对称性。完整的9D振转哈密顿量被划分为三个降维哈密顿量：5D刚性单体分子间振动哈密顿量和两个分子内振动哈密顿量，一个用于HDO单体（3D），另一个用于CO单体（1D），以及一个9D余项。降维哈密顿量分别对角化，并且它们的低能本征态的一小部分被纳入紧凑的最终9D乘积收缩基中，该基涵盖了络合物的所有内部、分子内和分子间自由度。9D振转哈密顿量在这个完全收缩基中对角化。计算表明，分别属于D键合和H键合异构体的本征态，分别指定为(\psi_{D})和(\psi_{H})，由于它们的波函数在PES上的两个极小值之一中几乎完全局域化，因此很容易识别。计算得到的两种单体的分子内振动频率根据模式要么发生蓝移要么发生红移。分子内振动模式的激发会影响各自分子内流形中低能(\psi_{D})和(\psi_{H})分子间振动态的能量。并与文献中可用的实验数据进行了比较。
