PyCI: A Python-scriptable library for arbitrary determinant CI

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Configuration Interaction (CI) is a fundamental quantum chemistry method.
• Developing efficient and flexible computational tools is crucial for advancing quantum chemistry.
• Existing tools may lack the flexibility for novel method development.

Purpose of the Study:

• Introduce PyCI, a free and open-source Python library.
• Facilitate arbitrary determinant-driven CI computations and their generalizations.
• Provide tools for method development in quantum chemistry.

Main Methods:

• Leverages Python for modern software development principles.
• Implements determinant-driven configuration interaction (CI) calculations.
• Delegates computationally intensive tasks to C++ for high performance.

Main Results:

• PyCI supports arbitrary CI computations and nonlinear parameter optimization.
• Includes functionality for residual correlation energy and spin-polarized density matrices.
• Demonstrates suitability for practical calculations and method development.

Conclusions:

• PyCI is a versatile and high-performance tool for quantum chemistry research.
• Its design facilitates the development and application of novel computational methods.
• The library is officially released with comprehensive documentation and testing.