Toward reliable density functional methods without adjustable parameters: The PBE0 model

We present an analysis of the performances of a parameter free density func tional model (PBE0) obtained combining the so called PBE generalized gradie nt functional with a predefined amount of exact exchange. The results obtai ned for structural, thermodynamic, kinetic and spectroscopic (magnetic, inf rared and electronic! properties are satisfactory and not far from those de livered by the most reliable functionals including heavy parameterization. The way in which the functional is derived and the lack of empirical parame ters fitted to specific properties make the PBE0 model a widely applicable method for both quantum chemistry and condensed matter physics. (C) 1999 Am erican Institute of Physics. [S0021-9606(99)30513-4].