Tight-binding calculation of formation energies in multicomponent oxides: Application to the MgO-CaO phase diagram

A. F. Kohan, G. Ceder
1996 Physical Review B (Condensed Matter)  
In this work we illustrate how the tight binding formalism can beused to accurately compute formation energies in multicomponent o xides. The large and complex unit cells of these systems make the application of precise ab initio LDA techniques very computer time demanding. Consequently, simpler but less accurate methods, such as potential models, are usually used but at the expense of obtaining just qualitatively correct results. In addition, many ad hoc assumptions have to be taken in
more » ... be taken in potential models to deal with charge transfer and many body e ects. The tight binding method can naturally incorporate these e ects in its formalism and still retain a low computational cost. Furthermore, we will show that it can accurately describe the energetics of oxides once its parameters are tted to precise LDA calculations. These considerations are important when computing temperature composition phase diagrams since formation energies of many ordered structures are the crucial input to the calculation. We used the CaO MgO system as a prototype system to illustrate the e ectiveness of the tight binding method. We show that by tting its parameters to ab initio plane wave pseu-
doi:10.1103/physrevb.54.805 pmid:9985345 fatcat:6wn5l5vb25evtk6xokqfp36fxy