Environment effects on effective magnetic exchange integrals and local spectroscopy of extended strongly correlated systems

The present work analyzes the importance of the different components of the environment effects on the local spectroscopy of extended, strongly-correlated systems. It has been found that the usual formal charge definition of the charge transfer and Madelung potential are far too crude for an accurate determination of the local excitation energies in embedded fragment calculations. A criterion for the validation of the embedding against the infinite system density of states has been proposed. (C) 2003 American Institute of Physics.