A Density Functional Theory based study of Electron Transport Through Ferrocene Compounds with Different Anchor Groups in Different Adsorption Configurations of A STM-setup

TL;DR

This study uses DFT and NEGF methods to analyze electron transport in ferrocene-based molecules with different anchor groups and configurations, revealing conductance behaviors and IV characteristics in STM setups.

Contribution

It introduces a combined DFT-NEGF approach to predict conductance and current-voltage patterns for ferrocene compounds with varied anchor groups and geometries.

Findings

Conductance does not decrease with increasing junction length.

Fermi level alignment explains conductance trends.

IV curves show minimal variation across configurations.

Abstract

In our theoretical study where we combine a nonequilibrium Green's function (NEGF) approach with density functional theory (DFT) we investigate compounds containing a ferrocene moiety which is connected to i) thiol anchor groups on both sides in a para-connection, ii) a pyridyl anchor group on one side in a meta-connection and a thiol group on the other side in a para-connection, in both cases with acetylenic spacers in between the Ferrocene and the anchors. We predict possible single molecule junction geometries within a scanning tunneling microscopy (STM) setup where we find that the conductance trend for the set of conformations are intriguing in the sense that the conductance does not decrease while the junction length increases which we analyze and explain in terms of Fermi level alignment. We also find a pattern for the current-voltage (IV) curves within the linear-response regime for both molecules we study, where the conductance variation with the molecular configurations is surprisingly small.