L. Ming et al., MOLECULAR-DYNAMICS STUDY OF ENERGY-TRANSFER IN BINARY COLLISIONS OF WATER-MOLECULES, The Journal of chemical physics, 104(22), 1996, pp. 9001-9015
Collisional energy transfer between two water molecules, one highly en
ergized (reactant) and another thermally equilibrated (medium) molecul
e, has been studied by classical molecular dynamics simulation over a
range of excitation energies and medium temperatures. The focus is on
the dependence of the energy transfer efficiency on the excitation ene
rgy, the medium temperature, and the gross features as well as the det
ails of the interaction between the molecules. High quality interactio
n potentials based on experimental data or quantum chemical calculatio
ns are used and the results are compared with those obtained by simple
r potentials constructed from Lennard-Jones pair potentials and point
charges. The dipolar contribution to the interaction is varied and the
molecules are partially or fully deuterated. The strong electrostatic
interaction is found to yield efficient energy transfer for small imp
act parameters but also a large cross section for water collisions. Th
e energy transfer efficiency is sensitive to the detailed form of the
interaction. However, if somewhat lower accuracy can be accepted then
simple potentials can be used. The energy transfer can be well fitted
by a conditional probability density based on a statistical model of e
quilibration among subsets of the degrees of freedom in the colliding
molecules. Rotational energy transfer is far more efficient than vibra
tional energy transfer. (C) 1996 American Institute of Physics.