  The first step toward the application of an effective non partial wave (PW)
numerical approach to few-body atomic bound states has been taken. The two-body
transition amplitude which appears in the kernel of three-dimensional
Faddeev-Yakubovsky integral equations is calculated as function of two-body
Jacobi momentum vectors, i.e. as a function of the magnitude of initial and
final momentum vectors and the angle between them. For numerical calculation
the realistic interatomic interactions HFDHE2, HFD-B, LM2M2 and TTY are used.
The angular and momentum dependence of the fully off-shell transition amplitude
is studied at negative energies. It has been numerically shown that, similar to
the nuclear case, the transition amplitude exhibits a characteristic angular
behavior in the vicinity of 4He dimer pole.
