State Representation Approach for Atomistic Time-Dependent Transport Calculations in Molecular Junctions

Area of Science:

• Quantum mechanics
• Condensed matter physics
• Materials science

Background:

• Simulating electron dynamics in open quantum systems is crucial for understanding transport phenomena.
• Existing methods often face challenges with equilibrium and non-equilibrium conditions.
• Atomistic modeling provides a detailed, first-principles approach to these systems.

Purpose of the Study:

• To introduce a novel, practical method for simulating time-dependent electron dynamics in open quantum systems using a finite atomistic model.
• To address limitations in current simulation techniques for non-equilibrium conditions.
• To enable accurate atomistic transport calculations in complex molecular junctions.

Main Methods:

• A Hamiltonian matrix transformation from atomistic to state representation of the molecular junction.
• Derivation of explicit damping and driving terms acting as electron sources and sinks.
• Application to various tight-binding model systems for numerical simulations.

Main Results:

• The method uniquely defines bias voltage and maintains thermal electronic distribution in finite lead models.
• Successfully simulated electron dynamics without violating Pauli's exclusion principle or density matrix positivity.
• Demonstrated applicability to complex, multilead molecular junction configurations.

Conclusions:

• The proposed method offers a practical and physically sound approach for atomistic time-dependent transport calculations.
• It provides a robust framework for investigating electron dynamics in realistic molecular junction models.
• This advancement facilitates deeper understanding of quantum transport phenomena in nanoscale devices.