  Employing a general variational method and perturbation theory, we derived
explicit solutions for the description of one-dimensional two species
Bose-Einstein condensates confined by a harmonic trap potential in an optical
lattice. We consider the system of two coupled Gross-Pitaevkii equations (GPE)
and derive explicit expressions for the chemical potentials and wavefunctions
in terms of the atom-atom interaction parameters and laser intensity. We have
compared our results with the numerical solutions of the GPE and performed a
quantitative analysis for the both considered methods. We underline the
importance of the obtained explicit solutions to characterize the density
profile or degree of miscibility of the two components.
