Lead geometry and transport statistics in molecular junctions.

Area of Science:

• Condensed matter physics
• Quantum chemistry
• Materials science

Background:

• Understanding charge transport in molecular junctions is crucial for molecular electronics.
• Non-equilibrium effects driven by bias voltage significantly alter transport properties.
• Accurate theoretical methods are needed to capture complex quantum phenomena.

Purpose of the Study:

• To numerically investigate charge transport and current fluctuations in molecular junctions under non-equilibrium conditions.
• To explore the impact of finite lead bandwidth on transport properties.
• To compare the sensitivity of mean current versus current fluctuations in probing transport phenomena.

Main Methods:

• Utilizing the inchworm quantum Monte Carlo (QMC) method for numerically exact simulations.
• Applying the QMC technique to molecular junctions with arbitrary lead geometries, exemplified by one-dimensional chains.
• Analyzing both average current and current fluctuations to characterize charge transport.

Main Results:

• Demonstrated the capability of the inchworm QMC method for diverse lead geometries.
• Revealed that finite lead bandwidth influences transport in ways not fully captured by quantum master equations.
• Identified an interaction-induced broadening of transport channels, observable across all applied voltages.
• Showcased current fluctuations as a more sensitive probe of this broadening compared to the mean current.

Conclusions:

• The inchworm QMC method provides a robust tool for studying non-equilibrium charge transport in molecular junctions.
• Finite lead bandwidth and electron-electron interactions introduce significant effects on transport properties.
• Current fluctuations offer deeper insights into quantum transport phenomena than average current measurements.