Abstract
The electronic structure and properties of cerium oxides ( and ) have been studied in the framework of the and implementations of density functional theory. The dependence of selected observables of these materials on the effective U parameter has been investigated in detail. The examined properties include lattice constants, bulk moduli, density of states, and formation energies of and . For , the results are in better agreement with experiment than the results whereas for the computationally more demanding both approaches give comparable accuracy. Furthermore, as expected, is much more sensitive to the choice of the U value. Generally, the PW91 functional provides an optimal agreement with experiment at lower U energies than LDA does. In order to achieve a balanced description of both kinds of materials, and also of nonstoichiometric phases, an appropriate choice of U is suggested for and schemes. Nevertheless, an optimum value appears to be property dependent, especially for . Optimum U values are found to be, in general, larger than values determined previously in a self-consistent way.
- Received 19 September 2006
DOI:https://doi.org/10.1103/PhysRevB.75.035115
©2007 American Physical Society