Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
J Chem Phys. 2018 Mar 14;148(10):104302. doi: 10.1063/1.5023155.
We present an investigation of vibrational features in water clusters performed by means of our recently established divide-and-conquer semiclassical approach [M. Ceotto, G. Di Liberto, and R. Conte, Phys. Rev. Lett. 119, 010401 (2017)]. This technique allows us to simulate quantum vibrational spectra of high-dimensional systems starting from full-dimensional classical trajectories and projection of the semiclassical propagator onto a set of lower dimensional subspaces. The potential energy surface employed is a many-body representation up to three-body terms, in which monomers and two-body interactions are described by the high level Wang-Huang-Braams-Bowman (WHBB) water potential, while, for three-body interactions, calculations adopt a fast permutationally invariant ab initio surface at the same level of theory of the WHBB 3-body potential. Applications range from the water dimer up to the water decamer, a system made of 84 vibrational degrees of freedom. Results are generally in agreement with previous variational estimates in the literature. This is particularly true for the bending and the high-frequency stretching motions, while estimates of modes strongly influenced by hydrogen bonding are red shifted, in a few instances even substantially, as a consequence of the dynamical and global picture provided by the semiclassical approach.
我们提出了一种通过我们最近建立的分而治之半经典方法来研究水分子团的振动特征的研究[M. Ceotto, G. Di Liberto 和 R. Conte, Phys. Rev. Lett. 119, 010401 (2017)]。这种技术允许我们从全维经典轨迹出发，并将半经典传播子投影到一组低维子空间上，从而模拟高维系统的量子振动谱。所采用的势能面是一种多达三体项的多体表示，其中单体和二体相互作用由高水平的 Wang-Huang-Braams-Bowman (WHBB) 水势描述，而对于三体相互作用，计算采用了相同理论水平的快速排列不变的从头计算表面的 WHBB 三体势。应用范围从水分子二聚体到由 84 个振动自由度组成的水分子十聚体。结果与文献中的先前变分估计基本一致。这对于弯曲和高频伸缩运动尤其如此，而受氢键强烈影响的模式的估计则由于半经典方法提供的动力学和全局图像而发生红移，在某些情况下甚至是实质性的。
