Psithon Functions: Invoking a Calculation

To allow arbitrarily complex computations to be performed, Psi4 is built upon the Python interpreter, with modifications termed Psithon. Sec. Psithon: Structuring an Input File describes the non-standard Python associated with clean molecule, basis, and option specification in the Psi4 input file. This documentation addresses the pure Python side- what functions allow the efficient compiled code to be run, what functions post-process and interact with that output, and how the ordinary (or ambitious) user can extent Psi4‘s functionality.

• Notes on Options
• Single-Point Energy, energy()
• Property
• Counterpoise Correct
• Geometry Optimization, optimize() and gradient()
• Harmonic Vibrational Analysis, frequency() and hessian()
• Database, database()
  • Output
  • Available Databases
• Complete Basis Set
  • Output
  • Extrapolation Schemes
  • Aliases
• Spectroscopic Constants for Diatomics
• Function Intercalls
• Embarrassing Parallelism
• cubeprop() Generation of cube files
  • Introduction
  • Cubeprop Tasks
  • Keywords
• Orbital Visualization with VMD
  • Script Prerequisites
  • Running the Script
  • Script Options