  Based on Sj\"{o}gren und Sjolander's Mode-Coupling(MC)-Model, we have
reformulated and calculated the memory kernel (MK) of the velocity
autocorrelation function (VACF)on a Ni$_{0.2}$Zr$_{0.8}$-liquid. Reformulating
means here that we have constructed the memory kernel of VACF for our binary
system, instead of one for one atomic system of the Sj\"{o}gren und Sjolander's
model. The data required for the theoretical calculations have been obtained
from molecular dynamics (MD) simulations. The theoretical results then are
compared with those directly obtained from computer simulation. We found,
although it exists a qualitative agreement between theoretical predictions and
simulation results, that quantitatively there is an deviations between both
results, especially for Zr-subsystem.
