Non-equilibrium Green's function transport theory for molecular junctions with general molecule-lead coupling and...

Area of Science:

• Quantum transport
• Molecular electronics
• Condensed matter physics

Background:

• Time-dependent effects in quantum transport are crucial for nanoscale devices.
• Current theoretical methods for charge dynamics in open quantum systems have limitations, particularly at low temperatures and with specific molecule-lead couplings.

Purpose of the Study:

• To develop a more versatile and efficient theoretical approach for calculating charge dynamics in quantum transport.
• To overcome the limitations of existing methods based on non-equilibrium Green's functions (NEGFs).

Main Methods:

• Applied a Chebyshev expansion to derive coupled ordinary differential equations within the NEGF formalism.
• Developed a scheme that is numerically efficient and independent of temperature and electrode band structure.
• Utilized a single-particle basis set to simplify matrix operations into vector operations.

Main Results:

• The new method overcomes restrictions on the functional form of molecule-lead coupling.
• Achieved numerical efficiency independent of temperature and electrode band structure.
• Demonstrated applicability to scenarios like coherent destruction of tunneling in molecular junctions under strong perturbations.

Conclusions:

• The Chebyshev expansion within NEGF offers a powerful and flexible tool for studying quantum transport.
• This method provides a significant advancement for simulating charge dynamics in complex molecular junctions.
• Enables more accurate and efficient design of nanoscale electronic devices.