Phenomenology of Λ-CDM Model: A Possibility of Accelerating Universe with Positive Pressure

Among various phenomenological Lambda models, a time-dependent model angstrom similar to H-3 is selected here to investigate the Lambda-CDM cosmology. The model can follow from dynamics, underlying the origin of Lambda. Using this model the expressions for the time-dependent equation of state parameter omega and other physical parameters are derived. It is shown that in H-3 model accelerated expansion of the Universe takes place at negative energy density, but with a positive pressure. It has also been possible to obtain the change of sign of the deceleration parameter q during cosmic evolution.