Official Resources
- Homepage: https://github.com/sheyua/RT-tddft
- Source Repository: https://github.com/sheyua/RT-tddft
- License: Open Source (based on Quantum ESPRESSO)
Overview
RT-tddft is a Real-Time Plane-Wave Time-Dependent Density Functional Theory code designed for simulating ultrafast electron dynamics, particularly focused on discharging nanostructures and non-equilibrium phenomena. It is built as an extension to Quantum ESPRESSO.
Scientific domain: Ultrafast electron dynamics, nanostructure discharge, non-equilibrium processes
Target user community: Researchers studying time-dependent phenomena in nanoscale systems using plane-wave DFT
Theoretical Methods
- Real-Time Time-Dependent DFT (RT-TDDFT)
- Plane-wave basis set implementation
- Explicit time propagation of Kohn-Sham equations
- Non-equilibrium electron dynamics
- Strong-field response simulations
Capabilities
- Ultrafast dynamics simulation of nanostructures
- Discharge dynamics modeling
- Real-time electron propagation in extended systems
- Non-equilibrium phenomena simulation
- Plane-wave accuracy for periodic and slab systems
Key Strengths
Specialized Focus:
- Designed for nanostructure dynamics
- Discharge process simulation
- Non-equilibrium electron behavior
QE Foundation:
- Built on Quantum ESPRESSO infrastructure
- Plane-wave basis accuracy
- Established pseudopotential library
Inputs & Outputs
-
Input formats:
- Quantum ESPRESSO-style input files
- Structure files
- Pseudopotentials (QE format)
-
Output data types:
- Time-dependent electronic properties
- Dynamics trajectories
- Charge evolution data
Interfaces & Ecosystem
- Quantum ESPRESSO base code integration
- Standard QE pseudopotential compatibility
- QE post-processing tools applicable
Performance Characteristics
- Basis: Plane-wave (systematic convergence)
- Parallelization: MPI (inherited from QE)
- Accuracy: Controlled by energy cutoff
- Time step: Requires small steps (attosecond scale) for stability
Advanced Features
- Discharge Dynamics: Specialized algorithms for simulating charge loss/gain in nanostructures.
- Strong Field Interaction: Coupling with external laser fields.
- Time-Dependent Charge Analysis: Tools to monitor charge fluctuations in real-time.
Computational Cost
- High: RT-TDDFT is computationally demanding, typically 10-100x more than ground state DFT.
- Scaling: Scales similarly to standard Plane-Wave DFT ($O(N^3)$) with system size, multiplied by thousands of time steps.
- Memory: Stores time-dependent wavefunctions, requiring significant RAM for large systems.
Best Practices
- Ground State: Ensure a well-converged ground state before propagation.
- Time Step: Use conservative time steps ($< 0.1$ atomic units) to avoid instability.
- Vacuum Padding: For nanostructures, ensure sufficient vacuum to avoid periodic image interactions, especially for discharge simulations.
Community and Support
- Source: GitHub repository (sheyua/RT-tddft).
- Issues: Use GitHub Issues for bug reports.
- Relation to QE: Leverages the broader Quantum ESPRESSO community for underlying DFT questions.
Limitations & Known Constraints
- Documentation: Limited README/docs
- Maintenance: Research code status
- Generality: Focused on specific applications
Comparison with Other Codes
- vs CE-TDDFT: Both QE-based RT-TDDFT; different focus areas
- vs SALMON: SALMON more mature with broader documentation
- Unique aspect: Nanostructure discharge specialization
Application Areas
- Nanostructure electronics
- Discharge dynamics
- Non-equilibrium transport
- Ultrafast phenomena in nanomaterials
Verification & Sources
Primary sources:
- GitHub repository: https://github.com/sheyua/RT-tddft
Confidence: VERIFIED
- Repository: ACCESSIBLE (GitHub)
- Code: Available and complete
- Status: Research-grade implementation
Verification status: ✅ VERIFIED