Large local energy fluctuations in water

Hideki Tanaka, Iwao Ohmine

Research output: Contribution to journalArticle

124 Citations (Scopus)

Abstract

A detailed analysis is made for the dynamical behavior of an individual water molecule in liquid water by using a classical molecular dynamics (MD) calculation. It is found that there exist very large potential energy fluctuations in water; a single water molecule can exhibit a fluctuation of the order of 10∼20 kcal/mol. These potential energy fluctuations can be classified into two categories; the fast component (10-14-10 -13 s) associated with librational motions of water molecules and the slow component (10-12-10-11 s) associated with water binding structure changes. Both amplitudes can be reached up to 10 kcal/mol. Due to strong Coulomb (dipole-dipole) interaction, small mutual geometrical changes, caused by the libration motions, induce large fast potential energy fluctuations. Due to large cohesion energy of the hydrogen bond and the nature of the water binding structure, there exist many water pair interactions which are unattactive or even repulsive; the water molecule potential (binding) energy distribution is inhomogeneous in space. This inhomogeneity alters as the water structure changes. Each water molecule then makes a transition from a stable binding to an unstable one with surrounding molecules and vice versa, inducing large potential energy changes in the picosecond order. A detailed analysis is made concerning how the hydrogen bonding pattern changes with water molecular motions. Significance of the existence of large water potential energy fluctuations on chemical processes is discussed.

Original languageEnglish
Pages (from-to)6128-6139
Number of pages12
JournalThe Journal of Chemical Physics
Volume87
Issue number10
Publication statusPublished - 1987
Externally publishedYes

Fingerprint

Water
water
Potential energy
energy
potential energy
Molecules
molecules
Hydrogen bonds
librational motion
dipoles
libration
cohesion
Binding energy
Molecular dynamics
energy distribution
inhomogeneity
binding energy
interactions
hydrogen bonds
molecular dynamics

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Large local energy fluctuations in water. / Tanaka, Hideki; Ohmine, Iwao.

In: The Journal of Chemical Physics, Vol. 87, No. 10, 1987, p. 6128-6139.

Research output: Contribution to journalArticle

Tanaka, H & Ohmine, I 1987, 'Large local energy fluctuations in water', The Journal of Chemical Physics, vol. 87, no. 10, pp. 6128-6139.
Tanaka, Hideki ; Ohmine, Iwao. / Large local energy fluctuations in water. In: The Journal of Chemical Physics. 1987 ; Vol. 87, No. 10. pp. 6128-6139.
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