Exponential-trigonometric basis functions in the Coulomb four-body problem

Basis functions of a new type-specifically, exponential-trigonometric funct ions depending on all six interparticle distances-have been proposed for th e Coulomb four-body problem. A method has been developed for computing nine -dimensional integrals determining the matrix elements of the Hamiltonian f or a four-body system and featuring these functions. The efficiency of the approach that relies on the proposed basis functions has been tested by cal culating the e(+)e(-)e(+)e(-), p(+)mu(-)p(+)mu(-), mu(+)e(-)mu(+)e(-), and p(+)e(-)p(+)e(-) molecules. (C) 2000 MAIK ''Nauka/Interperiodica".