Electronic structure boundary value problems without all of the atoms
H. T. Johnson, R. Phillips and L. B. Freund
Materials Research Society Symposium Proceedings, 538, 479–484 (1999).


A mixed atomistic/continuum technique is used to solve boundary value problems in strained semiconductors in which the mechanical and electronic properties are fully coupled. The technique, based on the quasicontinuum method, allows for the study of strain effects on electronic properties without the explicit treatment of all of the atoms in the structure of interest. A finite element framework is used to minimize the total energy in a body with respect to nodal positions. Within each element, tight binding atomistics is used to characterize cohesive energy, mechanical constitutive behavior and local electronic properties. The tight binding calculation of the electronic portion of the cohesive energy can be done in either k-space or real space. The technique thus lends itself naturally to the treatment of either ordered environments, such as the slowly varying deformation fields in a coherently strained body, or disordered environments, such as occur near an atomic scale defect or a bimaterial interface. As an example, a strained quantum wire device is considered.