GRW-space-time and certain type of energy-momentum tensor

In [9] author proved that 4-dimensional Lorentzian concircular structure [in brief (CS)(4)] space-time coincides with generalized Robertson Walker [in brief GRW] spacetime. Consequently, to study perfect fluid (CS)(4)-spacetime obeying Einstein equation under various curvature restrictions on energy-momentum tensor like semi-symmetric, Ricci semi-symmetric etc. are equivalent to study that of perfect fluid GRW-spacetime obeying Einstein equation. The paper attempts to point out the curvature conditions for which the nature of the fluid in GRW-spacetime obeying Einstein equation is sometimes phantom barrier and some other time remains quintessence barrier (De and Ljubica, 2015). (C) 2020 Elsevier B.V. All rights reserved.