Electron transport in real time from first-principles.

Area of Science:

• * Computational chemistry
• * Quantum dynamics
• * Molecular electronics

Background:

• * Traditional molecular conductance calculations rely on static non-equilibrium Green's function formalism with density functional theory (DFT).
• * Emerging time-dependent transport methods offer alternative approaches.
• * The driven Liouville-von Neumann equation presents a tunable, semi-empirical route for transport calculations.

Purpose of the Study:

• * To adapt the driven Liouville-von Neumann equation for a DFT framework.
• * To analyze the performance of this time-dependent approach for molecular conductance.
• * To develop a stable and accurate method for simulating electron transport in molecular systems.

Main Methods:

• * Implementation of the driven Liouville-von Neumann equation within an efficient all-electron DFT code using Gaussian basis functions.
• * Adaptation for quantum-dynamics simulations of large molecular systems.
• * Modification of the equation of motion for stable, unidirectional current in time-dependent DFT with small leads.

Main Results:

• * The initial perturbation significantly impacts electron dynamics stability in DFT, unlike in previous tight-binding studies.
• * A modified equation of motion is necessary for stable current propagation with smaller leads.
• * A novel procedure eliminates the rate parameter's influence on current-voltage curves.

Conclusions:

• * The adapted driven Liouville-von Neumann equation within DFT provides a robust framework for molecular conductance simulations.
• * The developed method yields accurate current-voltage characteristics for various hydrocarbons.
• * This approach shows significant promise for advancing the understanding of electron transport in molecular junctions.