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.
Key Features
- Theory:
- Density Functional Theory for ground-state calculations.
- LDA, GGA and OEP functionals available through libxc
- Time-dependent DFT for response.
- Density Functional Theory for ground-state calculations.
- 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.
- Through time-propagation:
- 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:
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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