1. Quickstart Guide

Quickstart Guide

• 1.1. About ORCA
• 1.2. Installation
  • 1.2.1. Download
  • 1.2.2. Installation
  • 1.2.3. Path Variables
  • 1.2.4. How do I install the xtb module?
• 1.3. Graphical User Interfaces (GUI)
• 1.4. Running ORCA
  • 1.4.1. A simple example
• 1.5. Hello water! Your first ORCA calculation
• 1.6. General Recommendations
  • 1.6.1. Know Your Methods
  • 1.6.2. Cost vs. Accuracy
  • 1.6.3. Creating the Right Model
  • 1.6.4. Matching Method and Property
  • 1.6.5. Some Method-specific Recommendations
• 1.7. Troubleshooting Problems in ORCA
  • 1.7.1. ORCA Does Not Run…
  • 1.7.2. Where is my ORCA Output?
  • 1.7.3. Sudden Termination of ORCA
  • 1.7.4. Incorrect Input File Syntax
    • 1.7.4.1. Unknown Simple Input Keyword
    • 1.7.4.2. Unknown Input Block Keyword
    • 1.7.4.3. Required Input is Missing
    • 1.7.4.4. Missing end Statement
    • 1.7.4.5. Missing Symbols
    • 1.7.4.6. Unrecognized Symbols
    • 1.7.4.7. Cannot Open Files
    • 1.7.4.8. End-of-file (EOF) Issues on Windows Machines
    • 1.7.4.9. Non-ASCII Characters
  • 1.7.5. Out of Memory (OOM)
  • 1.7.6. Disk Full
  • 1.7.7. Basis Set Linear Dependence
  • 1.7.8. Symmetry of Molecule Not as Expected
  • 1.7.9. Using Old ORCA Inputs
  • 1.7.10. Reproducing Results of Other Program Packages or Older ORCA Versions
  • 1.7.11. Orbitals Not Found
  • 1.7.12. Trouble Restarting Input File
  • 1.7.13. SCF Convergence Problems
    • 1.7.13.1. Example: Converging DFT for Open-Shell Transition Metals
  • 1.7.14. Troublesome Geometry Optimizations
    • 1.7.14.1. Imaginary Frequencies after Optimization
    • 1.7.14.2. Getting Unwanted Local Minima
    • 1.7.14.3. Issues with Optimization Convergence
  • 1.7.15. “Strange” Results for Energies and Properties