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Dynamics and structural changes of small water clusters on ionization
Author(s) -
Lee Han Myoung,
Kim Kwang S.
Publication year - 2013
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23296
Subject(s) - chemistry , ionization , molecular dynamics , water cluster , cluster (spacecraft) , density functional theory , perturbation theory (quantum mechanics) , ab initio , hydronium , coupled cluster , computational chemistry , ab initio quantum chemistry methods , molecule , ionization energy , chemical physics , ion , atomic physics , hydrogen bond , physics , organic chemistry , quantum mechanics , computer science , programming language
Despite utmost importance in understanding water ionization process, reliable theoretical results of structural changes and molecular dynamics (MD) of water clusters on ionization have hardly been reported yet. Here, we investigate the water cations [(H 2 O) n = 2–6 + ] with density functional theory (DFT), Möller–Plesset second‐order perturbation theory (MP2), and coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. The complete basis set limits of interaction energies at the CCSD(T) level are reported, and the geometrical structures, electronic properties, and infrared spectra are investigated. The characteristics of structures and spectra of the water cluster cations reflect the formation of the hydronium cation moiety (H 3 O + ) and the hydroxyl radical. Although most density functionals fail to predict reasonable energetics of the water cations, some functionals are found to be reliable, in reasonable agreement with high‐level ab initio results. To understand the ionization process of water clusters, DFT‐ and MP2‐based Born‐Oppenheimer MD (BOMD) simulations are performed on ionization. On ionization, the water clusters tend to have an Eigen‐like form with the hydronium cation instead of a Zundel‐like form, based on reliable BOMD simulations. For the vertically ionized water hexamer, the relatively stable (H 2 O) 5 + (5sL4A) cluster tends to form with a detached water molecule (H 2 O). © 2013 Wiley Periodicals, Inc.