We simulate a cluster of 144179 stars including 13107 primordial hard binaries ( 10 % of the total number of single stars and binary centers of mass ) , using direct integration of the equations of motion of all stars and binaries and incorporating the effects of stellar and binary evolution .
The initial conditions are representative of young dense star clusters in the Local Group and other nearby galaxies like the Antennae and M82 .
We find that the early phase of core collapse , driven by mass segregation , is not appreciably delayed by the presence of a large number of hard binaries .
By the end of the simulation , at an age of 115 Myr , the cluster radius has expanded by about a factor of two .
This may be explained as adiabatic expansion driven by the loss ( via stellar evolution ) of \sim 40 % of the initial total mass .
Binary dynamics apparently has little effect on the early cluster expansion .
During the evolution , the total binary fraction drops at a roughly constant rate of \sim 0.01 % per Myr .
The fraction of very hard binaries , however increases at about 0.025 % per Myr .
By the end of the simulation the cluster contains 37 binaries containing at least one black hole ; roughly half ( 17 ) of these contain two black holes .