  An important ingredient for the non-equilibrium evolution of partons at RHIC
and LHC is to have some physically reasonable initial conditions for the single
particle phase space distribution functions for the partons. We consider
several plausible parametrizations of initial conditions for the single
particle distribution function f_i(x,p) and fix the parameters by matching \int
f(x,p)p^\mu d \sigma_\mu to the invariant momentum space semi-hard parton
distributions obtained using perturbative QCD (pQCD), as well as fitting low
order moments of the distribution function. We consider parametrizations of
f_i(x,p) with both boost invariant and boost non-invariant assumptions. We
determine the initial number density, energy density and the corresponding
(effective) temperature of the minijet plasma at RHIC and LHC energies. For a
boost non-invariant minijet phase-space distribution function we obtain ~
30(140) /fm^3 as the initial number density, ~ 50(520) GeV/fm^3 as the initial
energy density and ~ 520(930) MeV as the corresponding initial effective
temperature at RHIC(LHC).
