  Some properties of minimal and nonminimal vector interactions in the
Duffin-Kemmer-Petiau (DKP) formalism are discussed. The conservation of the
total angular momentum for spherically symmetric nonminimal potentials is
derived from its commutation properties with each term of the DKP equation and
the proper boundary conditions on the spinors are imposed. It is shown that the
space component of the nonminimal vector potential plays a crucial role for the
confinement of bosons. The exact solutions for the vector DKP oscillator
(nonminimal vector coupling with a linear potential which exhibits an equally
spaced energy spectrum in the weak-coupling limit) for spin-0 bosons are
presented in a closed form and it is shown that the spectrum exhibits an
accidental degeneracy.
