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O: Fachverband Oberflächenphysik

O 57: New Methods: Theory

O 57.2: Talk

Wednesday, March 20, 2024, 16:30–16:45, MA 043

Efficient and Accurate Calculation of Tunneling Conductance in Molecular Junctions Using Density Functional Theory — •Enrique Montes and Héctor Vázquez — Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Prague 162 00, Czech Republic

We present a novel method for the calculation using density functional theory (DFT) of tunneling conductance in molecular junctions for thousands of junction structures. Conductance is estimated within a single scaling parameter by examining clusters where a molecule is bonded to one Au atom at each end and employing unconstrained ab initio molecular dynamics simulations [1]. This method yields accurate DFT-based conductance values across a wide range of geometries.

We investigate two junctions involving conjugated molecules. By examining scenarios where the central benzene ring can freely rotate or is constrained by chemical design [2], we uncover trends in transport properties and establish a clear mapping between molecular structure and junction conductance. Additionally, we evaluate the robustness of our methodology under varied conditions by employing different chemical linker groups (coupling regime) and metallic electrodes [3].

This method overcomes computational limitations, providing reliable conductance evaluation while reducing computational costs by a factor ∼400× as compared to DFT-NEGF transport calculations.

[1] H. Vázquez, J. Phys. Chem. Lett., 13, 9326 (2022).

[2] Y. S. Park, et al. J. Am. Chem. Soc., 131, 10820 (2009).

[3] T. A. Su, et al. Nat. Rev. Mater., 1, 16002 (2016).

Keywords: Density Functional Theory; Molecular Dynamics; Electron transport; Tunneling Coupling; Conductance