Conductance and polarization in quantum junctions

TY - JOUR

T1 - Conductance and polarization in quantum junctions

AU - Godby, R.W.

AU - Bokes, P.

N1 - © 2004 American Physical Society. This is an author produced version of a paper published in Physical Review B and uploaded in accordance with the publisher's self archiving policy.

PY - 2004/6/15

Y1 - 2004/6/15

N2 - We revisit the expression for the conductance of a general nanostructure -- such as a quantum point contact -- as obtained from the linear response theory. We show that the conductance represents the strength of the Drude singularity in the conductivity $\sigma(k,k';i\omega \to 0)$. Using the equation of continuity for electric charge we obtain a formula for conductance in terms of polarization of the system. This identification can be used for direct calculation of the conductance for systems of interest even at the {\it ab-initio} level. In particular, we show that one can evaluate the conductance from calculations for a finite system without the need for special ``transport'' boundary conditions.

AB - We revisit the expression for the conductance of a general nanostructure -- such as a quantum point contact -- as obtained from the linear response theory. We show that the conductance represents the strength of the Drude singularity in the conductivity $\sigma(k,k';i\omega \to 0)$. Using the equation of continuity for electric charge we obtain a formula for conductance in terms of polarization of the system. This identification can be used for direct calculation of the conductance for systems of interest even at the {\it ab-initio} level. In particular, we show that one can evaluate the conductance from calculations for a finite system without the need for special ``transport'' boundary conditions.

U2 - 10.1103/PhysRevB.69.245420

DO - 10.1103/PhysRevB.69.245420

M3 - Article

SN - 1098-0121

VL - 69

SP - Art. No. 245420

JO - Physical Review B

JF - Physical Review B

IS - 24

ER -