  Higher order parameters in the hard disk fluid are computed to investigate
the number, the life time and size of transient crystal nuclei in the
pre-freezing phase. The methodology introduces further neighbor shells bond
orientational order parameters and coarse-grains the correlation functions
needed for the evaluation of the stress autocorrelation function for the
viscosity. We successfully reproduce results by the previous collision method
for the pair orientational correlation function, but some two orders of
magnitude faster. This speed-up allows calculating the time dependent four body
orientational correlation between two different pairs of particles as a
function of their separation, needed to characterize the size of the transient
crystals. The result is that the slow decay of the stress autocorrelation
function near freezing is due to a large number of rather small crystal nuclei
lasting long enough to lead to the molasses tail.
