Octopus – scientific program aimed at the ab initio virtual experimentation

Octopus is a computer package aimed at the simulation of the electron-ion dynamics of finite systems, both in one and three dimensions, under the influence of time-dependent electromagnetic fields.

The electronic degrees of freedom are treated quantum mechanically within the time-dependent Kohn-Sham formalism, while the ions are handled classically. All quantities are expanded in a regular mesh in real space, and the simulations are performed in real time.

Although not optimized for that purpose, the program is also able to obtain static properties like ground-state geometries, or static polarizabilities. The method employed proved quite reliable and general, and has been successfully used to calculate linear and non-linear absorption spectra, harmonic spectra, laser induced fragmentation, etc. of a variety of systems, from small clusters to medium sized quantum dots.

Nuclei are described classically as point particles. Electron-nucleus interaction is described within the Pseudopotential approximation.

Features include:

  • Theory:
    • Density Functional Theory for ground-state calculations.
      • LDA, GGA and OEP functionals available through libxc
    • Time-dependent DFT for response.
  • Systems:
    • Works in 1D, 2D and 3D.
    • Periodic boundary conditions in 1, 2, or 3 directions (only for ground state calculations).
  • Linear Response:
    • Through time-propagation:
      • Static polarizabilities.
      • Absorption spectra (singlet, triplet).
    • Marc Casida’s formulation of response:
      • Electronic excitations.
    • Sterheimer (frequency dependent) linear response formalism:
      • Static and dynamic electric polarizabilities (including resonant response).
      • Static and dynamic electric first hyperpolarizabilities (including resonant response).
      • Static magnetic susceptibilities.
      • Phonon spectra.
  • Non-linear response – Dynamics:
    • Ehrenfest dynamics for the nuclei.
    • Real time TDDFT propagation.
    • Emission spectra, harmonic generation.
    • Optimal control theory.
    • Car-Parrinello Molecular Dynamics (development).
  • Technical:
    • Norm-conserving pseudopotentials (most commonly used formats).
    • Real space grid discretization (no basis sets).
    • Curvilinear coordinates.
    • Parallelization in domains and in states.
    • Runs both in single and double precision.

Website: octopus-code.org
Support: Wiki
Developer: Alberto Castro, Heiko Appel, Angel Rubio, Florian Lorenzen, Miguel A.L. Marques, Micael Oliveira, Carlo Andrea Rozzi, Xavier Andrade, Danilo Nitsche
License: GNU GPL v2

Octopus is written in Fortran. Learn Fortran with our recommended free books and free tutorials.

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