Eur. Phys. J. D (2016) 70: 246
https://doi.org/10.1140/epjd/e2016-60529-7

Regular Article

The investigation of structure and IR spectra for hydrated potassium ion clusters K⁺(H₂O)_n=1–16 by density functional theory^*

¹ Laboratory of Salt Resources and Chemistry, Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008, P.R. China
² The Mechanical Engineering College of Qinghai University, Xining 810001, P.R. China
³ Graduate University of Chinese Academy of Sciences, Beijing 100049, P.R. China

^a e-mail: frank_c_h_fang@126.com
^b e-mail: fangy8@isl.ac.cn

Received: 21 September 2015
Received in final form: 12 April 2016
Published online: 22 November 2016

Abstract

The hydration of K⁺(H₂O)_n has been widely studied and believe to be important for understanding solvent properties in biological and chemical systems. However, understanding the structure and the spectrum information K⁺(H₂O)_n with changing n is limited. Here, we investigated the clusters K⁺(H₂O)_n=1–16 and further studied the IR spectrums of the most stable clusters with density functional theory. The configuration, bond length, vibration frequency were given out. It shows that K⁺(H₂O)₈(H₂O)_n, a distorted square antiprism in inner layer, is the main configuration with hydration distance r_{K - OI} 0.296 nm when the hydration number n is bigger than 8. The saturated hydration number is 8 in the first hydration layer and the water molecules of the second hydration sphere have little effect on the inner ones when n> 8. A detailed classification about the hydrated water molecules was made according to the role of acceptor or donor hydrogen bonding in clusters. The vibration frequency of the different kinds of water molecules were also detailly identified. The results are valuable for further determination of the K⁺(H₂O)_n clusters in aqueous solutions.