CO2CO2 0.1.1

A Python package interfacing with the CO2CO2 shared library.

Molecule Potential Energy Library

This project provides a high-performance C++ library for calculating the potential energy of a CO₂ molecular system. The C++ routines are exposed to Python via both a ctypes-based wrapper and a (optional) pybind11 module, allowing you to leverage the speed of C++ with the ease-of-use of Python.

Project Structure

molecule-potential/            # Root directory
├── src/                     # C++ source files
│   ├── mbCO2CO2.cpp         # Implements the energy routines and exports functions
│   ├── mbCO2CO2.h           # Declarations for the energy routine functions:
│   │                         //   double p1b(double* xyz);
│   │                         //   double p2b(double* xyz);
│   │                         //   double sapt(double* xyz);
│   └── ... (other files)
├── python/                  # (Optional) pybind11 C++ binding module source
│   └── module.cpp           # Implements a Python module using pybind11
├── wrapper.py               # Python wrapper using ctypes to load the shared library
├── CMakeLists.txt           # CMake configuration to build the shared libraries
├── setup.py                 # Setup script for building and packaging the project for PyPI
├── README.md                # This file
└── LICENSE                  # License file (e.g., MIT License)

Installation

Prerequisites

• A C++ compiler and CMake (version 3.10 or above)
• Python 3.6+ with pip

Build the C++ Shared Library

This project uses CMake to build two targets:

• potential_energy: The core shared library built from all C++ source files in the src/ directory.
• molecule_module: A Python module (using pybind11) that links against potential_energy (optional if you prefer the ctypes wrapper).

To build the shared library:

1. Open a terminal in the project root and create a build directory:

   mkdir build
   cd build
   

2. Run CMake and build:

   cmake ..
   make
   

   The molecule_module shared library will be placed in build/python as defined in the CMakeLists.txt. The core shared library built from your src/ files will be named (for example) libCO2CO2.so.

Install the Package

The project can be installed as a Python package using pip. The provided setup.py script calls a custom build command to build the C++ shared library before packaging.

From the project root, run:

pip install .

This process will:

• Build the C++ shared library (via CMake or Makefile as configured).
• Package the Python wrapper (and optionally the pybind11 module) along with the shared library so that they can be imported in Python.

Usage

You can access the energy routines through the wrapper.py interface (which uses ctypes to load the shared library). For example:

from wrapper import p1b, p2b, sapt

# Example coordinates for 6 atoms (each atom has 3 coordinates);
# adjust these values as required by your application:
xyz = [
    0.0,  0.0,  0.000,   # Atom 1 (C)
    0.0,  0.0, -1.162,   # Atom 2 (O)
    0.0,  0.0,  1.162,   # Atom 3 (O)
    7.0,  0.0,  0.000,   # Atom 4 (C)
    7.0,  0.0, -1.162,   # Atom 5 (O)
    7.0,  0.0,  1.162    # Atom 6 (O)
]

energy_p1 = p1b(xyz)
energy_p2 = p2b(xyz)
energy_sapt = sapt(xyz)

print("Energy from p1b:", energy_p1)
print("Energy from p2b:", energy_p2)
print("Energy from sapt:", energy_sapt)

Note: If you built the pybind11 module (from python/module.cpp), you can alternatively import the module (e.g., import co2_potential) and call its functions (provided they are bound similarly to the ctypes wrappers).

Functionality

The library calculates the potential energy of a CO₂ system using multiple routines:

• p1b: Computes a portion of the potential energy (using routines from x1b).
• p2b: Computes another portion of the potential energy (using routines from x2b).
• sapt: Calculates energy contributions based on SAPT (Symmetry-Adapted Perturbation Theory) components.

The core computations are implemented in C++ for performance.

Contributing

Contributions are welcome! If you have suggestions for improvements or new features, please open an issue or submit a pull request.

License

This project is licensed under the MIT License. See the LICENSE file for details.