English

Are current discontinuities in molecular devices experimentally observable?

General Physics 2021-05-05 v1

Abstract

An ongoing debate in the first-principles description of conduction in molecular devices concerns the correct definition of current in the presence of non-local potentials. If the physical current density j=(ie/2m)(ΨΨΨΨ){\bf j}=(-ie\hbar/2m)(\Psi^* \nabla \Psi- \Psi \nabla \Psi^*) is not locally conserved but can be re-adjusted by a non-local term, which current should be regarded as real? We prove that the extended Maxwell equations by Aharonov-Bohm give the e.m.\ field generated by such currents without any ambiguity. For an oscillating dipole we show that the radiated electrical field has a longitudinal component proportional to ωP^ \omega \hat{P}, where P^\hat{P} is the anomalous moment I^(x)xd3x\int \hat{I}(\mathbf{x})\mathbf{x} d^3x and I^\hat{I} is the space-dependent part of the anomaly I=tρ+jI=\partial_t \rho+\nabla \cdot \mathbf{j}. In the case of a stationary current in a molecular device, a failure of local current conservation causes a "missing field" effect that can be experimentally observable, especially if its entity depends on the total current.

Keywords

Cite

@article{arxiv.2104.14342,
  title  = {Are current discontinuities in molecular devices experimentally observable?},
  author = {F. Minotti and G. Modanese},
  journal= {arXiv preprint arXiv:2104.14342},
  year   = {2021}
}

Comments

22 pages, 5 figures

R2 v1 2026-06-24T01:37:59.877Z