Revealing molecule-internal mechanisms that control phonon heat transport through single-molecule junctions by a genetic algorithm

Abstract

Measurements of the thermal conductance of single-molecule junctions have recently been reported for the first time. It is presently unclear, how much the heat transport can be controlled through molecule-internal effects. The search for molecules with lowest and highest thermal conductance is complicated by the gigantic chemical space. Here we describe a systematic search for molecules with a low or a high phononic thermal conductance using a genetic algorithm. Beyond individual structures of well performing molecules, delivered by the genetic algorithm, we analyze patterns and identify the different physical and chemical mechanisms to suppress or enhance phonon heat flow. In detail, mechanisms revealed to reduce phonon transport are related to the choice of terminal linker blocks, substituents and corresponding mass disorder or destructive interference, meta couplings and molecule-internal twist. For a high thermal conductance, the molecules should instead be rather uniform and chain-like. The identified mechanisms are systematically analyzed at different levels of theory, and their significance is classified. Our findings are expected to be important for the emerging field of molecular phononics.

main text (16 pages, 9 figures) and supporting information (12 pages, 9 figures)

References in corpus (21)

• Dependence of Single Molecule Junction Conductance on Molecular Conformation
• Quantum thermal transport in nanostructures
• Active learning machine learns to create new quantum experiments
• SELFIES and the future of molecular string representations
• Nonequilibrium Green's function method for quantum thermal transport
• Artificial Intelligence and Machine Learning for Quantum Technologies
• Large Conductance Variations in a Mechanosensitive Single-Molecule Junction
• Tilt-angle landscapes and temperature dependence of the conductance in biphenyl-dithiol single-molecule junctions
• Conduction mechanisms in biphenyl-dithiol single-molecule junctions
• Cluster-based density-functional approach to quantum transport through molecular and atomic contacts
• First-principles calculation of the thermoelectric figure of merit for [2,2]paracyclophane-based single-molecule junctions
• Graphical prediction of quantum interference-induced transmission nodes in functionalized organic molecules
• Length dependence of the thermal conductance of alkane-based single-molecule junctions: An ab-initio study
• Quantum mechanical modeling of anharmonic phonon-phonon scattering in nanostructures
• Tuning the thermal conductance of molecular junctions with interference effects
• Phonon Interference Effects in Molecular Junctions
• Thermal conductance and thermoelectric figure of merit of C${}_{60}$-based single-molecule junctions: electrons, phonons, and photons
• Designing $\pi$-stacked molecular structures to control heat transport through molecular junctions
• Thermal conductance of metallic atomic-size contacts: Phonon transport and Wiedemann-Franz law
• Phonon transport in a one-dimensional harmonic chain with long-range interaction and mass disorder
• Phononic heat conductance of gold atomic contacts: Coherent versus incoherent transport