Molecular conductance calculations of single-molecule junctions using projection-based density functional embedding.

Area of Science:

• Computational Chemistry
• Molecular Electronics
• Condensed Matter Physics

Background:

• Single-molecule junctions (SMJs) are crucial for understanding electron transport at the nanoscale.
• Accurate theoretical prediction of SMJ properties is essential for designing molecular electronic devices.
• Traditional methods often struggle to precisely model the complex electronic interactions within SMJs.

Purpose of the Study:

• To develop and validate a new computational strategy for modeling electron transport in SMJs.
• To improve the accuracy of predicting zero-bias conductance in SMJs.
• To investigate the impact of different exchange-correlation functionals on SMJ electronic properties.

Main Methods:

• Employed a density-functional theory in density-functional theory (DFT-in-DFT) embedding technique.
• Combined DFT-in-DFT with the non-equilibrium Green's function (NEGF) method.
• Utilized the CAM-B3LYP functional for the molecule and the PBE functional for the electrodes in transport calculations.

Main Results:

• Achieved a substantial improvement in the accuracy of predicted zero-bias conductance compared to standard PBE calculations.
• Demonstrated the effectiveness of using distinct functionals for the molecule and electrode domains.
• Identified changes in molecular energy levels and electrode-molecule interactions as key factors for improved accuracy.

Conclusions:

• The proposed DFT-in-DFT embedding method offers a more accurate approach for modeling SMJs.
• Tailoring exchange-correlation functionals for specific components of SMJs is critical for precise electronic property prediction.
• This work provides a pathway for more reliable computational design of molecular electronic devices.