skip to main content

SciTech ConnectSciTech Connect

Title: Communication: Isotopic effects on tunneling motions in the water trimer

We present results of ring polymer molecular dynamics simulations that shed light on the effects of nuclear quantum fluctuations on tunneling motions in cyclic [H{sub 2}O]{sub 3} and [D{sub 2}O]{sub 3}, at the representative temperature of T = 75 K. In particular, we focus attention on free energies associated with two key isomerization processes: The first one corresponds to flipping transitions of dangling OH bonds, between up and down positions with respect to the O–O–O plane of the cluster; the second involves the interchange between connecting and dangling hydrogen bond character of the H-atoms in a tagged water molecule. Zero point energy and tunneling effects lead to sensible reductions of the free energy barriers. Due to the lighter nature of the H nuclei, these modifications are more marked in [H{sub 2}O]{sub 3} than in [D{sub 2}O]{sub 3}. Estimates of the characteristic time scales describing the flipping transitions are consistent with those predicted based on standard transition-state-approximation arguments.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. Departamento de Química Inorgánica Analítica y Química-Física e INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 1428 Buenos Aires (Argentina)
  2. Department of Chemistry, Rice University, Houston, Texas 77251-1892 (United States)
  3. (Argentina)
Publication Date:
OSTI Identifier:
22493727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 6; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMS; CHEMICAL BONDS; FLUCTUATIONS; FREE ENERGY; HEAVY WATER; HYDROGEN; ISOMERIZATION; ISOTOPE EFFECTS; MOLECULAR DYNAMICS METHOD; MOLECULES; POLYMERS; REDUCTION; TUNNEL EFFECT; VISIBLE RADIATION