Official Resources
- Homepage: https://etprogram.org/
- Documentation: https://etprogram.org/user_manual.html
- Source Repository: https://gitlab.com/eT-program/eT
- License: GNU General Public License v3.0
Overview
eT is a quantum chemistry program specialized in calculating molecular response properties and time-dependent phenomena using coupled cluster theory. Developed with focus on response properties, excited states, and spectroscopic calculations, eT implements efficient coupled cluster methods with particular emphasis on equations-of-motion and linear response approaches for accurate molecular properties.
Scientific domain: Coupled cluster, response properties, excited states, spectroscopy
Target user community: Spectroscopy researchers, response property calculations, CC method users
Theoretical Methods
- Coupled cluster (CC2, CCSD, CC3)
- Equations-of-motion coupled cluster (EOM-CC)
- Linear response coupled cluster
- Time-dependent coupled cluster
- Hartree-Fock
- Response properties
- Excited states
- Transition properties
- Spectroscopic properties
Capabilities (CRITICAL)
- Ground-state coupled cluster
- Excited states (EOM-CC)
- Response properties
- Molecular properties
- Spectroscopic calculations
- Transition moments
- Oscillator strengths
- UV/Vis spectra
- Linear response
- Time-dependent properties
- High-accuracy calculations
- Research-quality results
Sources: Official website (https://etprogram.org/)
Key Strengths
Response Properties:
- Specialized focus
- CC response theory
- Accurate properties
- Transition moments
- Spectroscopic data
Coupled Cluster:
- CC2, CCSD, CC3
- EOM-CC for excitations
- High accuracy
- Benchmark quality
- Production methods
Spectroscopy:
- UV/Vis calculations
- Excitation energies
- Oscillator strengths
- Transition properties
- Experimental comparison
Open Source:
- GPL v3 licensed
- GitLab repository
- Free to use
- Community development
- Transparent code
Research Tool:
- Method development
- Property calculations
- Benchmark studies
- Accurate results
- Academic focus
Inputs & Outputs
-
Input formats:
- Text-based input
- Molecular coordinates
- Basis set specifications
- Method settings
-
Output data types:
- Energies
- Excitation energies
- Properties
- Transition moments
- Spectroscopic data
Interfaces & Ecosystem
-
Development:
- GitLab repository
- Community contributions
- Research tool
-
Analysis:
- Property extraction
- Spectroscopy analysis
- Standard tools
- Custom scripts
Workflow and Usage
Typical Workflow:
- Prepare molecular structure
- Select CC method
- Choose basis set
- Configure response properties
- Run eT calculation
- Analyze results
Running eT:
et input.inp
# Runs coupled cluster calculation
Advanced Features
EOM-CC:
- Equations-of-motion
- Excited states
- Accurate excitations
- Multiple states
- Transition properties
Response Theory:
- Linear response
- Time-dependent properties
- Molecular properties
- Spectroscopic calculations
- High accuracy
CC Methods:
- CC2 (approximate)
- CCSD (standard)
- CC3 (high accuracy)
- Gradients (selected)
- Production quality
Performance Characteristics
- Speed: Moderate (high-level CC)
- Accuracy: Excellent for properties
- System size: Small to medium molecules
- Scalability: Typical CC scaling
- Typical: Research calculations
Computational Cost
- CC2: Moderate cost
- CCSD: Expensive
- CC3: Very expensive
- Response: Additional cost
- Production: Research-level feasible
Limitations & Known Constraints
- System size: Limited by CC scaling
- Community: Smaller, specialized
- Documentation: Research-level
- Features: Focused on properties
- Platform: Linux primarily
- Development: Academic/research
Comparison with Other Codes
- vs CFOUR: eT specialized for response properties
- vs Dalton: Similar focus, different implementation
- vs PSI4: eT more specialized
- Unique strength: CC response properties, EOM-CC, spectroscopy focus
Application Areas
Spectroscopy:
- UV/Vis calculations
- Excitation energies
- Transition moments
- Oscillator strengths
- Experimental comparison
Response Properties:
- Molecular properties
- Linear response
- Time-dependent
- High accuracy
- Benchmark calculations
Excited States:
- EOM-CC calculations
- Multiple states
- Accurate excitations
- State properties
- Transition densities
Method Development:
- CC response research
- Algorithm testing
- Benchmark studies
- Property methods
Best Practices
Method Selection:
- CC2 for screening
- CCSD for production
- CC3 for benchmarks
- Appropriate for system
- Balance accuracy/cost
Basis Sets:
- Appropriate for properties
- Augmented when needed
- Convergence testing
- Balance size/accuracy
Response Calculations:
- Select properties carefully
- Converge SCF well
- Check stability
- Validate results
Community and Support
- Open-source (GPL v3)
- GitHub repository
- Academic development
- Research community
- Limited production support
Educational Resources
- GitHub documentation
- Source code
- Published papers
- CC theory literature
- Response property references
Development
- GitHub-based development
- Academic contributors
- Research focus
- Ongoing improvements
- Community input
Research Applications
- Response property calculations
- Spectroscopy predictions
- Benchmark studies
- Method development
- High-accuracy properties
Technical Innovation
CC Response:
- Efficient implementations
- Response theory
- Property calculations
- Specialized algorithms
- Research quality
EOM-CC:
- Excited state methods
- Accurate excitations
- Transition properties
- Multiple states
- Production implementations
Verification & Sources
Primary sources:
- Official website: https://etprogram.org/
- Documentation: https://etprogram.org/user_manual.html
- GitLab repository: https://gitlab.com/eT-program/eT
- Published papers on eT methodology
Secondary sources:
- Coupled cluster literature
- Response property methods
- EOM-CC references
- Spectroscopy calculations
Confidence: LOW_CONF - Research code, specialized focus, smaller community
Verification status: ✅ VERIFIED
- Official website: ACCESSIBLE (https://etprogram.org/)
- Documentation: ACCESSIBLE (user manual)
- Source code: OPEN (GitLab, GPL v3)
- Community support: GitLab, academic
- Development: Active on GitLab
- Specialized strength: Coupled cluster response properties, EOM-CC excited states, spectroscopic calculations, molecular properties, linear response theory, benchmark-quality accuracy