Ab Inito Calculation of Paraelectric State of Pbtio3

We have performed a first-principles study of structural. electronic and optical properties ofcubic stale of pbtio3 by means of first principles with density functional theory using fullpotential linearized augmented plane wave (fp-lapw) method with generalized gradientapproximation (gga ), engle-vesco approximation (eva) and local spin densityapproximation with the aim of hubbard parameter u, (lsda+u). the calculated electronicstructure and charge density yield a band gap of (3.3 ev) at the x point in the brillouin zonethe theoretical optical properties of and energy loss (eel) spectrum yield a static refractiveindex of (2.83) and plasmon energy of (2.+ ev) for cubic phase of pbtio3.