  Locally rotationally symmetric (L.R.S.) Bianchi type II stiff fluid
cosmological model is investigated. To get the deterministic model of the
universe, we have assumed a condition $A=B^{m}$ between metric potentials
$A,~B$ where $n$ is the constant. It is shown that the vacuum energy density
$\Lambda$ is positive and proportional to $\frac{1}{t^{2}}$. The values of
deceleration parameter $q$, matter-energy density $\Omega_{m}$ and dark-energy
density $\Omega_{\Lambda}$ are found to be in good agreement with the values
obtain from 5-years WMAP observations. the predicted value of the jerk
parameter agrees with the SNLS SNIa and X-ray galaxy cluster distance data but
does not with the SNIa gold sample data. In general, the model represent
accelerating, shearing and non-rotating universe.The physical and geometrical
behavior of these models are also discussed.
