  We investigate the hypothesis that stars form in aggregates of binary systems
and that the dynamical evolution of these aggregates leads to the observed
properties of binary stars in the Galactic field. We assume that the initial
distribution of periods is flat in logP, where P is the orbital period in days,
and 3<logP<7.5. We distribute 200 binaries in aggregates with half mass radii R
corresponding to the range from tightly clustered to isolated star formation,
and follow the subsequent evolution of the stellar systems by direct N-body
integration. Hardening and softening of binary systems do not significantly
increase the number of orbits with logP<3 and logP>7.5. After the cluster with
R=0.8pc disintegrates we obtain a population which consists of about 60 per
cent binary systems with a period distribution for logP>4 as is observed and in
which the G-dwarf binaries have a mass ratio distribution which agrees with the
observed distribution. This result indicates that the majority of Galactic
field stars may originate from a clustered star formation mode. We invert the
orbit depletion function and obtain an approximation to the initial binary star
period distribution for star formation in the dominant mode cluster. Comparison
with the measured distribution of orbits for pre-main sequence stars suggests
that the initial distribution may not depend on the star formation environment.
Inverse dynamical population synthesis suggests that the Galactic field stellar
mass function may be related to the stellar density at birth in the most
common, or dominant, mode of star formation.
