  In this paper, we have applied a three-dimensional approach for calculation
of the relativistic nucleon-nucleon potential. The quadratic operator relation
between the non-relativistic and the relativistic nucleon-nucleon interactions
is formulated as a function of relative two-nucleon momentum vectors, which
leads to a three-dimensional integral equation. The integral equation is solved
by the iteration method, and the matrix elements of the relativistic potential
are calculated from non-relativistic ones. Spin-independent Malfliet-Tjon
potential is employed in the numerical calculations, and the numerical tests
indicate that the two-nucleon observables calculated by the relativistic
potential are preserved with high accuracy.
