Abdalla, MCBNojiri, S.Odintsov, S. D.2014-05-202014-05-202005-03-07Classical and Quantum Gravity. Bristol: Iop Publishing Ltd, v. 22, n. 5, p. L35-L42, 2005.0264-9381http://hdl.handle.net/11449/23278We discuss modified gravity which includes negative and positive powers of curvature and provides gravitational dark energy. It is shown that in GR plus a term containing a negative power of curvature, cosmic speed-up may be achieved while the effective phantom phase (with w less than -1) follows when such a term contains a fractional positive power of curvature. Minimal coupling with matter makes the situation more interesting: even 1/R theory coupled with the usual ideal fluid may describe the (effective phantom) dark energy. The account of the R(2) term (consistent modified gravity) may help to escape cosmic doomsday.L35-L42engCarta10.1088/0264-9381/22/5/L01WOS:000228261400001Acesso aberto