A multiconfigurational pair-density functional theory approach to molecular junctions

Abstract

Due to their small size and unique properties, single-molecule electronics have long seen research interest from experimentalists and theoreticians alike. From a theoretical standpoint, modeling these systems using electronic structure theory can be difficult due to the importance of electron correlation in the determination of molecular properties, and this electron correlation can be computationally expensive to consider, particularly multiconfigurational correlation energy. In this work, we develop a new approach for the study of single-molecule electronic systems, denoted NEGF-MCPDFT, which combines multiconfiguration pair-density functional theory (MC-PDFT) with the non-equilibrium Green's function formalism (NEGF). The use of MC-PDFT with NEGF allows for the efficient inclusion of both static and dynamic electron correlation in the description of the junction's electronic structure. CASSCF wave functions are used as references in the MC-PDFT calculation, and like with any active space method, effort must be made to determine the proper orbital character to include in the active space. We perform conductance and transmission calculations on a series of alkanes (predominantly single-configurational character) and benzyne (multiconfigurational character), exploring the role that active space selection has on the computed results. For the alkane junctions explored (where dynamic electron correlation dominates), the MCPDFT-NEGF results agree well with DFT-NEGF results. For the benzyne junction (which has significant static correlation), we see clear differences in the MCPDFT-NEGF and DFT-NEGF results, and evidence that NEGF-MCPDFT is capturing additional electron correlation effects beyond those provided by the PBE functional.

References in corpus (20)

• Density functional method for nonequilibrium electron transport
• Electron transmission through molecules and molecular interfaces
• Single-Molecule Circuits with Well-Defined Molecular Conductance
• ab initio modeling of open systems: charge transfer, electron conduction, and molecular switching of a C_{60} device
• First-Principles Based Matrix-Green's Function Approach to Molecular Electronic Devices: General Formalism
• Charge Transport in Single Au|Alkanedithiol|Au Junctions: Coordination Geometries and Conformational Degrees of Freedom
• Improvements on non-equilibrium and transport Green function techniques: the next-generation transiesta
• The Kondo effect in C${}_{60}$ single-molecule transistors
• Advances and challenges in single-molecule electron transport
• Automated Selection of Active Orbital Spaces
• Cheap and near exact CASSCF with large active spaces
• CASSCF with Extremely Large Active Spaces using the Adaptive Sampling Configuration Interaction Method
• Applicability of the Wide-Band Limit in DFT-Based Molecular Transport Calculations
• Quantitative Current-Voltage Characteristics in Molecular Junctions from First Principles
• A DFT-based Molecular Transport Implementation in ADF/BAND
• Length dependence of the thermal conductance of alkane-based single-molecule junctions: An ab-initio study
• Tunnelling in alkanes anchored to gold electrodes via amine end groups
• Nonequilibrium configuration interaction method for transport in correlated quantum systems
• A wave function based ab initio non-equilibrium Green's function approach to charge transport
• Charge-Transfer Selectivity and Quantum Interference in Real-Time Electron Dynamics: Gaining Insights from Time-Dependent Configuration Interaction Simulations