Multiscale approach to electron transport dynamics.

Area of Science:

• Computational Physics
• Materials Science
• Quantum Chemistry

Background:

• Simulating molecular transport requires open quantum boundary conditions, often computationally expensive.
• Existing methods using large electrodes with first-principles calculations demand high computational resources.

Purpose of the Study:

• To develop a computationally efficient hybrid multiscale scheme for molecular simulations.
• To accurately model transport properties in nanostructures by combining DFT with semiempirical methods.

Main Methods:

• A hybrid scheme coupling semiempirical tight-binding electrodes with a density functional theory (DFT) described molecule/device.
• Implementation in microcanonical and grand-canonical (Driven Liouville von Neumann equation) frameworks.
• Validation via calculation of tunneling decay constants and quantum interference effects.

Main Results:

• The hybrid method achieves negligible computational cost for massive electrodes while preserving DFT accuracy.
• Demonstrated accurate computation of tunneling decay in polyacetylene and quantum interference in aromatic rings.
• Investigated the significant impact of electric fields on polyacetylene conductance.

Conclusions:

• The proposed multiscale scheme offers a powerful and efficient tool for simulating quantum transport in nanostructures.
• This method enables precise control of electron flow in nanocircuits through external electric fields.