In order to specify cosmologically motivated initial conditions for major galaxy mergers ( mass ratios \leq 4:1 ) that are supposed to explain the formation of elliptical galaxies we study the orbital parameters of major mergers of cold dark matter halos using a high-resolution cosmological simulation .
Almost half of all encounters are nearly parabolic with eccentricities e \approx 1 and no correlations between the halo spin planes or the orbital planes .
The pericentric argument \omega shows no correlation with the other orbital parameters and is distributed randomly .
In addition we find that 50 % of typical pericenter distances are larger than half the halo ’ s virial radii which is much larger than typically assumed in numerical simulations of galaxy mergers .
In contrast to the usual assumption made in semi-analytic models of galaxy formation the circularities of major mergers are found to be not randomly distributed but to peak around a value of \epsilon \approx 0.5 .
Additionally all results are independent of the minimum progenitor mass and major merger definitions ( i.e .
mass ratios \leq 4:1 ; 3:1 ; 2:1 ) .