A wave function expansion for the study of tetra-atomic molecules in hyperspherical coordinate systems

In this work, we focus on the tetra-atomic molecule problem in hyperspheric al coordinates. In particular, we explore the system of hyperspherical coor dinates as used, for example, by Ohrn and Linderberg (1983, Molec. Phys., 4 9, 53). We consider a wave function expansion which facilitates the analyti c integration of the kinetic energy operator for the nine degrees of freedo m.