Current-constrained one-electron reduced density-matrix theory for non-equilibrium steady-state molecular...

Area of Science:

• Molecular electronics
• Quantum chemistry
• Condensed matter physics

Background:

• The pursuit of miniaturization in electronics drives interest in single-molecule circuit elements.
• Traditional methods (e.g., non-equilibrium Green's function density functional theory) calculate current from voltage.
• A novel approach, current-constrained density-matrix theory, calculates voltage from a current constraint.

Purpose of the Study:

• To extend the current-constrained density-matrix theory.
• To adapt the theory from a two-electron reduced density-matrix (2-RDM) to a one-electron reduced density-matrix (1-RDM) formulation.
• To broaden the applicability of the method to various quantum chemical theories.

Main Methods:

• Formulation of a one-electron reduced density-matrix (1-RDM) approach for current-constrained theory.
• Extension of the theory to be compatible with Hartree-Fock, density functional theory, and tight-binding methods.
• Application of the 1-RDM method to calculate the intrinsic resistance of molecular systems.

Main Results:

• Successful extension of current-constrained density-matrix theory to a 1-RDM formulation.
• Demonstration of the method's applicability across different quantum chemical frameworks.
• Computation of the theoretical, intrinsic resistance for acenes and phenacenes.

Conclusions:

• The 1-RDM current-constrained method offers a new perspective for analyzing molecular conductivity.
• This formulation provides a versatile tool for studying charge transport in single-molecule electronics.
• The findings pave the way for designing and understanding future molecular electronic devices.