Approximate density functionals applied to molecular quantum dots.
Recently, molecular quantum dots (MQDs) have been investigated experimentally and found to exhibit the Kondo effect. The Kondo effect leads to an enhancement of the zero-voltage conductance. Here, we study a finite cluster model of a MQD by means of Kohn-Sham density functional theory. Furthermore, employing an implementation of Landauer's formula, we calculate the conductance of the dot. We find that the electronic structure and the molecular conductance depend strongly on the exchange-correlation functional employed. While the local spin density approximation and the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation qualitatively reproduce certain features of the Kondo effect, PBE hybrid does not. Based on the MQD, we discuss the limitations of using density functional theory to model molecular electronic devices.
Zhuang
Min
M
Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Québec H3C 3J7, Canada.
Rocheleau
Philippe
P
Ernzerhof
Matthias
M