Calculation of near edge structure

Near edge fine structure has the potential to solve problems related to loc alised electronic states and bonding. Theory and calculation provide the li nk between electronic or structural properties and features observed in an electron loss spectrum. A hierarchy of approximations for the calculation o f near edge structure features is introduced and the importance of using a self-consistent charge density and potential is emphasised. The use of vari ous electronic structure calculation methods and their application to near edge structure calculation is reviewed. Finally, core hole effects are disc ussed and examples presented for cubic BN showing that the core hole mainly enhances intensity near threshold. (C) 1999 Elsevier Science B.V. All righ ts reserved.