Rotational relaxation of water

Rotational relaxation of water:

symbol	explanation	experimental value, and method
HH	H-H axis	$\tau _{2}=2.0$ps (H-H dipolar relaxation NMR)
OH	O-H axis	$\tau _{2}=1.95$ps ($^{17}$O-H dipolar relaxation NMR)
$\mu$	dipolar axis	not measurable, but related to bulk dielectric relaxation
$\perp$	normal to the molecule plane	not measurable

References

1. David van der Spoel, Paul J. van Maaren, and Herman J. C. Berendsen "A systematic study of water models for molecular simulation: Derivation of water models optimized for use with a reaction field", J. Chem. Phys. 108 10220 (1998)