Rotational dynamics of a solvated dipole: A molecular dynamics study of dielectric friction

摘要

Molecular dynamics has been used to examine the influence of the permanent dipole moment on the rotational diffusion of a diatomic molecule in liquid water. Several runs were made for various values of the dipole moment of the solute ranging from 0 to 20 D. The resultant rotational diffusion times compare favorably with dielectric friction theories up to about 17 D, but for dipole moments larger than this, the time constants are seen to increase much more rapidly than can be explained by dielectric friction theories. This deviation from dielectric friction theory is discussed in terms of a local change in solvation structure.