Reliability of the Heitler-London approach for the exchange coupling between electrons in semiconductor nanostructures

TL;DR

This paper evaluates the reliability of the Heitler-London approach for calculating exchange coupling between electrons in semiconductor nanostructures, showing improvements and overcoming previous limitations at short interdot distances.

Contribution

It demonstrates that with a suitable variational wave function, the Heitler-London method can be significantly improved for estimating exchange coupling in double-well potentials.

Findings

Improved estimates for exchange coupling J using simple variational wave functions.

Overcomes artifacts of the HL method at short interdot distances.

Achieves agreement with analytic models for donor-type potentials.

Abstract

We calculate the exchange coupling J between electrons in a double-well potential in a two-dimensional semiconductor environment within the Heitler-London (HL) approach. Two functional forms are considered for the double-well potential. We show that by choosing an appropriate and relatively simple single-electron variational wave function it is possible, within the HL approach, to significantly improve the estimates for J. In all cases the present scheme overcomes the artifacts and limitations at short interdot distances, previously attributed to the HL method, where unphysical triplet ground states have been found, and leads to an overall agreement with analytic interpolated expressions for J obtained for a donor-type model potential.