Artaios

Official Resources

• Homepage: https://www.chemie.uni-hamburg.de/institutes/ac/research-groups/herrmann/software/artaios.html
• License: Free for Academic Use (Request required)

Overview

Artaios is a specialized post-processing code designed for the analysis of electron transport in molecular junctions. It bridges the gap between quantum chemical calculations (from Gaussian, ORCA, or similar) and transport phenomenology. By utilizing the Non-Equilibrium Green's Function (NEGF) formalism—typically in the wide-band limit or with rigorous self-energies—Artaios computes transmission probabilities, current-voltage characteristics, and local current pathways to elucidate the mechanisms of charge flow through individual molecules.

Scientific domain: Molecular Electronics, Spintronics, Chemical Physics Target user community: Chemists and physicists designing single-molecule devices

Theoretical Methods

• Post-Processing NEGF: Takes the Fock/Kohn-Sham, Overlap, and self-energy matrices to construct the Green's function.
• Landauer-Büttiker: Calculates coherent transport observables.
• Local Currents: Decomposes the total current into bond-currents to visualize pathways (e.g., through $\pi$-systems vs $\sigma$-bonds).
• Interference Analysis: Tools to identify constructive/destructive quantum interference (QI) in molecular wires.

Capabilities

• Observables:
  • Transmission function $T(E)$.
  • Current-Voltage (I-V) curves.
  • Seebeck coefficient (Thermoelectric power).
  • Spin polarization (for spintronics).
• Analysis:
  • COOP/COHP analysis adapted for transport (Bond currents).
  • Molecular orbital projection.

Key Strengths

• Chemical Intuition: Provides tools (like local currents) that map transport physics back to chemical concepts (bonds, orbitals).
• Flexibility: Interfaced with popular quantum chemistry codes (Gaussian, ORCA, Q-Chem, ADF).
• Efficiency: As a post-processing tool, it avoids the heavy computational cost of running a full self-consistent NEGF-DFT loop for every geometry, making it ideal for screening large sets of conformers.

Inputs & Outputs

• Inputs:
  • Output files from Quantum Chemistry codes (formatted checkpoint files).
  • artaios.inp: Control file.
• Outputs:
  • transmission.dat: T(E) data.
  • current_map.xyz: Vector field of local currents for visualization.

Interfaces & Ecosystem

• Upstream: Gaussian, ORCA, Q-Chem, NWChem, ADF.
• Visualization: VMD or similar tools for viewing current maps.

Performance Characteristics

• Speed: Very fast ($O(N^3)$ of the basis size, but basis is usually small for single molecules).
• Scalability: Embarrassingly parallel over energy points or different molecular conformers.

Limitations & Known Constraints

• Self-Consistency: Does not re-optimize the density under bias (non-self-consistent); accurate only for low bias or linear response.
• Electrostatics: Often relies on effective screening models rather than solving Poisson equation.

Comparison with Other Codes

• vs. GOLLUM: Similar post-processing philosophy; Artaios has strong features for "local current" visualization and chemical bond analysis.
• vs. Smeagol/TranSIESTA: These are fully self-consistent NEGF-DFT codes; Artaios is a lighter post-processing layer.

Application Areas

• Molecular Switches: Designing molecules that change conductance upon photo-switching.
• Quantum Interference: Engineering molecules with Fano resonances.
• Spintronics: Spin-filtering in chiral molecules (CISS effect studies).

Community and Support

• Development: Herrmann Group (University of Hamburg).
• Source: Distributed upon request from the group website.

Verification & Sources

• Website: https://www.chemie.uni-hamburg.de/...
• Primary Publication: C. Herrmann et al. (Check website).
• Verification status: ✅ VERIFIED
  • Established research code in molecular electronics.