Electron transport in a Pt-CO-Pt nanocontact: First-principles calculations

TL;DR

This study uses first-principles calculations to analyze electron transport in platinum nanocontacts with and without CO molecules, revealing stable configurations and conductance features consistent with experimental observations.

Contribution

The paper identifies a stable tilted bridge configuration for Pt-CO-Pt contacts with conductance near 0.5G_0, explaining experimental conductance peaks.

Findings

Pt contacts differ between point contacts and short chains

Stable tilted bridge configuration has conductance close to 0.5G_0

Conductance mainly influenced by local d-band at Pt atoms

Abstract

We have performed first-principles calculations for the mechanic and electric properties of pure Pt nano-contacts and a Pt contact with a single CO molecule adsorbed. For the pure Pt contacts we see a clear difference between point contacts and short chains in good agreement with experiments. We identify a tilted bridge configuration for the Pt-CO-Pt contact, which is stable and has a conductance close to $0.5G_0$ ($G_0=2e^2/h$), and we propose that this structure is responsible for an observed peak at $0.5G_0$ in the conductance histogram for Pt exposed to a CO gas. We explain the main features of the transmission function for the Pt-CO-Pt contact, and show that the conductance is largely determined by the local $d$-band at the Pt apex atoms.