Improved molecular conductance predictions using wavefunction-in-DFT quantum embedding.

Area of Science:

• Computational Chemistry
• Condensed Matter Physics
• Molecular Electronics

Background:

• Accurate modeling of electron transport in single-molecule junctions (SMJs) is crucial for molecular electronics.
• Traditional density functional theory (DFT) methods may struggle to capture electron correlation effects in the molecular component.

Purpose of the Study:

• To present a novel electronic structure methodology for describing electron transport in SMJs.
• To enhance the accuracy of transport calculations by incorporating correlated many-electron wavefunction models.

Main Methods:

• Developed a projection-based quantum embedding technique within non-equilibrium Green's function (NEGF) theory.
• Combined correlated wavefunction methods (HF, SOS-ADC(2), CCSD) for the molecular region with DFT for metallic electrodes.
• Utilized Dyson orbitals for constructing a specialized molecular Hamiltonian.

Main Results:

• Demonstrated the method's effectiveness for benzene-1,4-diamine based SMJs.
• Achieved improved zero-bias conductance predictions compared to standard DFT (PBE) calculations.
• Showcased the importance of describing electronic correlation within the molecule.

Conclusions:

• The proposed wavefunction-in-DFT embedding scheme offers a systematic approach for accurate SMJ transport modeling.
• Provides a balance between computational cost and accuracy by selecting appropriate electronic structure methods.
• Highlights the impact of electronic correlation on electron transport phenomena.