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 General Public License v2.0

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

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