Inst High Energy Phys, Beijing 100049, Peoples R China
; SW Univ, Chongqing 400715, Peoples R China
; CCAST, World Lab, Beijing 100080, Peoples R China
; Ctr Theoret Nucl Phys, Natl Lab heavy Ion Accelerator, Lanzhou 730000, Peoples R China
Using the potentials derived from vector-meson-exchanges, the K (K) over bar, DK, B (K) over bar, D (D) over bar, B (B) over bar, BD, (D) over barK, BK and B (B) over bar systems are studied. Possible S-wave bound-states of two pseudoscalar mesons are discussed. We find that systems of DB, D (D) over bar, B (B) over bar and DK with isospin 0 are likely to form S-wave bound states via strong interactions while the others are unlikely to be bound by the strong interaction sector alone. With the Coulomb potential, the K+K- system can form an atomic bound state - the kaonium. The influence of the one-meson-exchange potential on the ground-state energy of the kaonium and its decay widths to pi pi and pi eta are evaluated.