We perform a cosmological simulation in order to model the growth and evolution of Population III ( Pop III ) stellar systems in a range of host minihalo environments .
A Pop III multiple system forms in each of the ten minihaloes , and the overall mass function is top-heavy compared to the currently observed initial mass function in the Milky Way .
Using a sink particle to represent each growing protostar , we examine the binary characteristics of the multiple systems , resolving orbits on scales as small as 20 AU .
We find a binary fraction of \sim 35 % , with semi-major axes as large as 3000 AU .
The distribution of orbital periods is slightly peaked at \la 900 yr , while the distribution of mass ratios is relatively flat .
Of all sink particles formed within the ten minihaloes , \sim 50 % are lost to mergers with larger sinks , and \sim 50 % of the remaining sinks are ejected from their star-forming disks .
The large binary fraction may have important implications for Pop III evolution and nucleosynthesis , as well as the final fate of the first stars .