We present molecular dynamics simulations of lithium silicate melts with (L
i2O)(x)(SiO2)(1-x) with Li2O concentrations x = 0.01, x = 0.1 and x = 0.5 i
n equilibrium conditions for temperatures down to 1500 K. The partial pair
correlation functions are determined and compared with recent experimental
data. The dynamics of the individual species is characterized via the mean
square displacement. From the temperature dependence of the long-time diffu
sion constant we extract information about its activation energy. Interesti
ngly, for x = 0.5 the extrapolation of the diffusion constant to temperatur
es below 700 K shows good agreement with experimental tracer diffusion data
. In agreement with experiment, the length scale beyond which the dynamics
becomes diffusive systematically varies with lithium concentration. Analysi
s of the van Hove self correlation function reveals how the occurrence of h
opping processes as well as the presence of dynamic heterogeneities at low
temperatures is correlated with the Li2O concentration.