Energy Estimates for Local Chemical Processes in Condensed Matter

摘要

The problem of local chemical processes in condensed matter is reviewed, with special attention given to the associated changes in energy. The model adopted is based on a partition of the system into a local and an external region: it is assumed that all important changes in the electronic structure and nuclear configuration related with the process considered take place in the local region, while the solution for the unperturbed host system can be taken as a reference in the external region. This Ansatz allows an accurate description of the electronic structure in a neighborhood of the defect to be obtained [10, 16], However, disregarding long range effects can result in large errors in the estimated value of the defect formation energy, AjB. A strategy for estimating these long range contributions is outlined, based on the linear response properties of the host system and on the entity of the perturbation created by the defect in the local region. The case of the color center in the MgO monolayer is used to show the importance of one of these contributions to AJ3, the so-called charge balance correction, by comparing embedded-cluster with supercell results.