Simple iterative procedure for optimized effective potential method in density functional theory and in current density functional theory

The optimized effective potential (OEP) method in the density functional theory is reformulated on the basis of the variable coupling constant scheme. By this formulation, the origin of the so-called 'orbital shift' in the OEP method is revealed. The method leads to a simple iterative procedure of the OEP method using the Thomas-Fermi model. This method is extended to the OEP method in the current density functional theory (CDFT) and in the time-dependent CDFT. As a numerical test, the procedure in the nonmagnetic time-independent case is applied to the exchange-only calculation of the Be atom. The present procedure converges more quickly than that of Kummel and Perdew [Phys. Rev. B 68 (2003) 035103].