Fractional quantum hall effect at even-denominator filling fractions

The recently discovered fractional quantum Hall effect at $\frac{5}{2}$ filling has been studied by the standard technique of finite electron systems in a periodic rectangular geometry. We have evaluated the low-lying excitations and the correlation functions for ½ filling in the lowest Landau level, as well as in the next Landau level with the lowest Landau level fully filled. The results indicate that the origin of the $\frac{5}{2}$ effect is due to the same incompressible-quantum-fluid state which manifests itself at odd-denominator fractions.