Official Resources
- Homepage: https://octopus-code.org/
- Documentation: https://octopus-code.org/documentation/
- Source Repository: https://gitlab.com/octopus-code/octopus
- License: GNU General Public License v2.0
Overview
Octopus is a scientific program for the ab initio simulation of electron-ion dynamics using time-dependent density-functional theory (TDDFT) and real-space grids. It specializes in real-time propagation for studying ultrafast processes, optical properties, and electron dynamics.
Scientific domain: Ultrafast dynamics, optical properties, electron-ion dynamics, strong-field physics
Target user community: Researchers studying time-dependent phenomena, optical response, laser-matter interaction
Theoretical Methods
- Time-Dependent Density Functional Theory (TDDFT)
- Real-time TDDFT propagation
- Density Functional Theory (DFT) for ground state
- Real-space finite-differences method
- LDA, GGA, hybrid functionals
- Optimal control theory (OCT)
- Ehrenfest molecular dynamics
- Multi-system calculations (electron-ion, photon-electron)
- Non-adiabatic dynamics
- Casida equation for linear response
Capabilities (CRITICAL)
- Ground-state DFT calculations
- Real-time TDDFT for electron dynamics
- Optical absorption spectra
- Time-resolved spectroscopy simulation
- Strong-field physics (high-harmonic generation)
- Photoionization and photoemission
- Ehrenfest molecular dynamics
- Optimal control for laser pulse design
- Non-linear optical properties
- Plasmonic excitations
- Photon-electron coupling
- Multi-component systems
- Geometry optimization
- Vibrational analysis
- GPU acceleration for real-time propagation
Sources: Official Octopus documentation, cited in 7/7 source lists
Inputs & Outputs
-
Input formats:
- inp file (Octopus input format)
- XYZ coordinate files
- Pseudopotential files
-
Output data types:
- Time-dependent observables
- Absorption spectra
- Electronic densities (real-space grids)
- Time-propagated wavefunctions
- Ehrenfest trajectories
- Photoelectron spectra
Interfaces & Ecosystem
Computational Cost
- RT-TDDFT: Very expensive compared to linear response; scales as $O(N_{steps} \times N_{grid} \times N_{states})$.
- Grid Spacing: Cost increases as $(1/h)^3$ or $(1/h)^4$ depending on order.
- Parallelization: Good MPI scaling significantly reduces wall-time.
- GPU: 10-50x speedups possible for propagation, making medium systems feasible.
Limitations & Known Constraints
- Real-space grids: Require convergence testing for grid spacing
- Pseudopotentials: Limited to norm-conserving
- System size: Real-time TDDFT expensive; ~100-500 atoms typical
- Time propagation: Long simulations memory and time intensive
- k-point sampling: Best for finite systems or Gamma-point
- Hybrid functionals: Computationally expensive
- Learning curve: TDDFT concepts require understanding
- Parallelization: MPI and GPU but efficiency varies
- Platform: Primarily Linux/Unix
Verification & Sources
Primary sources:
- Official website: https://octopus-code.org/
- Documentation: https://octopus-code.org/documentation/
- GitLab repository: https://gitlab.com/octopus-code/octopus
- A. Castro et al., Phys. Status Solidi B 243, 2465 (2006) - Octopus code
- X. Andrade et al., J. Phys.: Condens. Matter 24, 233202 (2012) - Real-space TDDFT
Secondary sources:
- Octopus tutorials and workshops
- Published ultrafast dynamics applications
- Strong-field physics studies
- Confirmed in 7/7 source lists (claude, g, gr, k, m, q, z)
Confidence: CONFIRMED - Appears in all 7 independent source lists
Verification status: ✅ VERIFIED
- Official homepage: ACCESSIBLE
- Documentation: COMPREHENSIVE and ACCESSIBLE
- Source code: OPEN (GitLab)
- Community support: Active (mailing list, GitLab)
- Academic citations: >500 (main papers)
- Active development: Regular releases, GPU optimization