Effects of vertex corrections on diagrammatic approximations applied to the study of transport through a quantum dot

Abstract

In the present work, we calculate the conductance through a single quantum dot weakly coupled to metallic contacts. We use the spin-1/2 Anderson model to describe the quantum dot, while considering a finite Coulomb repulsion. We solve the interacting system using the non-crossing-approximation (NCA) and the one-crossing approximation (OCA). We obtain the linear response conductance as a function of temperature and energy position of the localized level. From the comparison of both approximations we extract the role of the vertex corrections, which are introduced in the OCA calculations and neglected in the NCA scheme. As a function of the energy position, we observe that the diagrams omitted within NCA are really important for appropriately describing transport phenomena in Kondo systems as well as in the mixed valence regime. On the other hand, as a function of temperature, the corrections introduced by OCA partly recover the universal scaling properties known from numerical approaches such as the Numerical Renormalization Group(NRG).

5 pages, 5 figures

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• Dynamical Mean-Field Theory within the Full-Potential Methods: Electronic structure of Ce-115 materials
• Universal scaling in transport out of equilibrium through a single quantum dot using the noncrossing approximation
• Conductance through an array of quantum dots
• Conserving approximations in direct perturbation theory: new semianalytical impurity solvers and their application to general lattice problems
• Dynamic susceptibilities of the single impurity Anderson model within an enhanced non-crossing approximation

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