GOLLUM

A next generation quantum transport simulation tool

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GOLLUM is a program that computes the charge, spin and thermal transport properties of multi-terminal nano-scale junctions.

The program can compute transport properties of either user-defined systems described by a tight-binding Hamiltonian, or more material-specific properties of systems composed of real atoms described by DFT Hamiltonians.

GOLLUM delivers the following functionalities

1. Simulates multi-terminal devices

2. Reads either Tight-Binding or DFT hamiltonians

3. Computes charge transport

- Number of open scattering channels- Electronic transmission and reflection coefficients- Shot-noise

4. Computes heat transport

- Thermal conductance due to both electrons and phonons- Thermopower (Seebeck coefficient)- Peltier coefficient- Thermoelectric Figure of merit ZT

5. Computes spin transport

- Collinear spins systems- Non-collinear spins systems- Systems with strong spin-orbit interaction

6. Computes phonon transport

- Number of open phononic scattering channels- Phononic transmission and reflection coefficients

7. Computes the full scattering matrix

8. Computes zero-voltage as well as I-V curves

9. Handles vdW and LDA+U functionals

10. Allows spectral adjustment for strongly correlated systems

11. Computes band-structure, density of state and number of open channels of leads

12. Covers large samples enabling to analize ballistic to diffusive regimes

13. Interfaced to DFT codes:

  • Siesta code which uses a localized basis set,
  • Plane wave codes such as Castep, VASP, ABINIT and Quantum-Espresso through Wannier Hamiltonians from the Wannier90 code.

Version 3.0 will come with

  • Kondo & Coulomb blockade physics

  • Magnetic field and integer quantum Hall effect

  • Info about Local charge, spin, current and spin-current densities inside the scattering region

  • Scripts to handle multiscale simulations