libcint is a C library (also with a Fortran API) to evaluate one- and two-electron integrals for GTOs.

The InChI (IUPAC International Chemical Identifier) algorithm turns chemical structures into machine-readable strings of information. InChIs are unique to the compound they describe and can encode absolute stereochemistry making chemicals and chemistry machine-readable and discoverable. A simple analogy is that InChI is the bar-code for chemistry and chemical structures.

XCFun is a library of exchange-correlation functionals with arbitrary-order derivatives for density functional theory.

MoleQueue is a system-tray resident desktop application for abstracting, managing, and coordinating the execution of tasks both locally and on remote computational resources. Users can set up local and remote queues that describe where the task will be executed. Each queue can have programs, with templates to facilitate the execution of the program. Input files can be staged, and output files collected using a standard interface.

GROMACS is a versatile package to perform molecular dynamics, i.e. simulate the Newtonian equations of motion for systems with hundreds to millions of particles. It is primarily designed for biochemical molecules like proteins, lipids and nucleic acids that have a lot of complicated bonded interactions, but since GROMACS is extremely fast at calculating the nonbonded interactions (that usually dominate simulations) many groups are also using it for research on non-biological systems, e.g. polymers. GROMACS supports all the usual algorithms you expect from a modern molecular dynamics implementation.

Open Babel is a chemical toolbox designed to speak the many languages of chemical data. It's a collaborative project allowing anyone to search, convert, analyze, or store data from molecular modeling, chemistry, solid-state materials, biochemistry, or related areas.

Spglib is a library for finding and handling crystal symmetries written in C. Spglib can be used to:

1. Find symmetry operations

2. Identify space-group type

3. Wyckoff position assignment

4. Refine crystal structure

5. Find a primitive cell

6. Search irreducible k-points

RDKit is a C++ and Python library for cheminformatics, which includes (among other things) the analysis and modification of molecules in 2D and 3D and descriptor generation for machine learning.

This package contains a library and programs for canonicalization of SMILES and MOL files, molecular structure fingerprinting and rendering molecules.

PySCF (Python-based Simulations of Chemistry Framework) is a Python library for quantum chemistry calculations and method development. Most of the functionality is implemented in Python, while computationally critical parts are implemented in C.

RingDecomposerLib is a library for the calculation of unique ring families, relevant cycles, the smallest set of smallest rings and other ring topology descriptions.

Avogadro libraries provide 3D rendering, visualization, analysis and data processing useful in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas.

geomeTRIC is a Python library and program for geometry optimization of molecular structures, which works with different external quantum chemistry (and molecular mechanics) softwares.

This extension to python-pyscf provides calculations of different electromagnetic properties for molecules and crystals.

PyMOL is a capable molecular viewer and renderer. It can be used to prepare publication-quality figures, to share interactive results with your colleagues, or to generate pre-rendered animations.

coordgenlibs contains algorithms to generate 2D coordinates of molecules including macrocycles and metal complexes. It has an emphasis on quality rather than speed.

FreeSASA is a command line tool and C-library for calculating SASAs. By default Lee & Richards' algorithm is used, but Shrake & Rupley's is also available. Both can be parameterized to arbitrary precision, and for high resolution versions of the algorithms, the calculations give identical results.

This package is a wrapper around simple-dftd3 and dftd4 for use with pyscf.

YAeHMOP contains a program and library for performing extended Hückel calculations and analyzing the results.

TRAJNG (Trajectory next generation) is a program library for handling molecular dynamics (MD) trajectories. It can store coordinates, and optionally velocities and the H-matrix. Coordinates and velocities are stored with user-specified precision.

GEMMI is a C++ library for macromolecular crystallography. It can be used for working with

1. macromolecular models (content of PDB, PDBx/mmCIF and mmJSON files),

2. refinement restraints (CIF files),

3. reflection data (MTZ and mmCIF formats),

4. data on a 3D grid (electron density maps, masks, MRC/CCP4 format)

5. crystallographic symmetry.

maeparser is a parser for Schrodinger Maestro files.

Avogadro 2 is an advanced molecule editor and visualizer designed for use in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas. It offers flexible high quality rendering and a powerful plugin architecture.

Chez Scheme is both a programming language and a high-performance implementation of that language. The language is a superset of R6RS Scheme with numerous extensions, including native threads, non-blocking I/O, local modules, and much more. Chez Scheme compiles source expressions incrementally to machine code, providing the speed of compiled code in an interactive system. The system is intended to be as reliable and efficient as possible, with reliability taking precedence over efficiency if necessary.