arXiv subjects

A. Martinez-Garcia

Publications and source records attributed to A. Martinez-Garcia.

4 recordsLinked to original sources

arXiv2026

ANT:UI: An interactive 3D tool for preparing ANT.Gaussian molecular junction geometries

ANT.UI is a Python graphical interface that automates the construction of molecular-junction geometries for NEGF-DFT quantum transport calculations. Through a real-time 3D viewer, users interactively position electrodes and molecules and generate complete, ready-to-run input files for Gaussian and ANT.Gaussian without manual scripting. Dedicated Pull, Grid, and Rotation assistants further automate electrode-pulling sequences, surface scans, and step-wise rotation studies, with optional geometry-optimisation chaining across each sequence. By replacing a process that previously demanded days of custom scripting with a point-and-click workflow, ANT.UI accelerates research in theoretical molecular electronics and lowers the barrier to entry for new users. The software also exports all constructed geometries in standard XYZ format, allowing direct reuse in molecular dynamics codes or third-party visualization tools without manual reformatting.

cond-mat.mes-hall↗

arXiv2025

Exploring Three-Atom-Thick Gold Structures as a Benchmark for Atomic-Scale Calibration of Break-Junction Systems

We present an in-depth study of electronic transport in atomic-sized gold contacts using Break-Junction (BJ) techniques under cryogenic and ambient conditions. Our experimental results, supported by classical molecular dynamics (CMD) simulations and ab initio calculations, provide compelling evidence for the formation of three-atom-thick structures in gold nanocontacts under tensile stress. These findings extend previous studies that confirmed the existence of one- and two-atom-thick chains. Beyond identifying these novel atomic configurations, we introduce a fast and robust calibration method for Break-Junction systems, leveraging the characteristic length of these structures to convert piezo displacement into absolute distance in angstroms. Our approach presents a novel and robust method for calibrating atomic distances in atomic conductor systems at both cryogenic and room temperatures. The results also enable the assessment of electrode sharpness, even at room conditions.

cond-mat.mes-hall↗

arXiv2023

Evidence of an Off-resonant Electronic Transport Mechanism in Helicenes

Helical molecules have been identified as potential candidates for investigating electronic transport, spin filtering, or even piezoelectricity. However, the description of the transport mechanism is not straightforward in single molecular junctions. In this work, we study the electronic transport in break junctions of a series of three helical molecules: dithia[$n$]helicenes, with $n=7, 9, 11$ molecular units, and detail the synthesis of two kinds of dithia[11]helicenes, varying the location of the sulfur atoms. Our experimental study demonstrates low conductance values that remain similar across different biases and molecules. Additionally, we assess the length dependence of the conductance for each helicene, revealing an exponential decay characteristic of off-resonant transport. This behaviour is primarily attributed to the misalignment between the energy levels of the molecule-electrodes system. The length dependence trend described above is supported by \textit{ab initio} calculations, further confirming the off-resonant transport mechanism.

cond-mat.mes-hall↗

arXiv2023

Unraveling the Interplay between Quantum Transport and Geometrical Conformations in Monocyclic Hydrocarbons Molecular Junctions

In the field of molecular electronics, particularly in quantum transport studies, the orientation of molecules plays a crucial role. This orientation, with respect to the electrodes, can be defined through the cavity of ring-shaped monocyclic hydrocarbon molecules. In this manuscript, we unveil the geometrical conformation of these molecules when they are trapped between two atomically sharp electrodes through a combination of dynamic simulations, electronic transport calculations based on density functional theory, and break junction experiments under room conditions. Moreover, we present a novel criterion for determining the molecular orientation of benzene, toluene, (aromatic) and cyclohexane (aliphatic) solvents. Our findings for the identification of the molecular orientations on gold metal nanocontacts and their associated transport properties, can improve the understanding of molecular electronics using more complex cyclic hydrocarbons.

cond-mat.mtrl-sci↗