Single channel conductance of H$_2$ molecules attached to platinum or palladium electrodes

TL;DR

This study provides a theoretical analysis of hydrogen molecule conductance between platinum and palladium electrodes, revealing stable bridging configurations and quantized conductance values near 1 G0.

Contribution

It offers new insights into the bonding configurations and conductance quantization of H2 molecules with Pt and Pd electrodes, highlighting the role of localized states in transport.

Findings

Conductance is approximately 0.9 G0 for Pt and 0.6 G0 for Pd.

The bridging configuration is stable over a wide range of electrode distances.

Transport occurs mainly through the anti-bonding state, not hybridized bonding states.

Abstract

We report a detailed theoretical study of the bonding and conduction properties of an hydrogen molecule joining either platinum or palladium electrodes. We show that an atomic arrangement where the molecule is placed perpendicular to the electrodes is unstable for all distances between electrodes. In contrast, the configuration where the molecule bridges the electrodes is stable in a wide range of distances. In this last case the bonding state of the molecule does not hybridize with the leads and remains localized within the junction. As a result, this state does not transmit charge so that electronic transport is carried only through the anti-bonding state. This fact leads to conductances of 1 $G_0$ at most, where $G_0=2e^2/h$. We indeed find that G is equal to 0.9 and 0.6 $G_0$ for Pt and Pd contacts respectively.