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

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.

qcint is an optimized version of libcint, a C library (also with a Fortran API) to evaluate one- and two-electron integrals for Gaussian type functions.

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.

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.

libmsym is a C library dealing with point group symmetry in 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.

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

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

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.

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

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.

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.

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.

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

This package provides a portable and efficient R[4567]RS implementation of regular expressions, supporting both POSIX syntax with various (irregular) PCRE extensions, as well as SCSH's SRE syntax, with various aliases for commonly used patterns.

Chez Scheme is a self-hosting compiler: building it requires ``boot files'' containing the Scheme-implemented portions compiled for the current platform. (Chez can then cross-compile bootfiles for all other supported platforms.)

This package provides boot files for the released version of Chez Scheme bootstrapped by chez-scheme-for-racket. Chez Scheme 9.5.4 or any later version can be used for bootstrapping. Guix ultimately uses the Racket package cs-bootstrap to bootstrap its initial version of Chez Scheme.

ChezWEB is a system for doing Knuthian style WEB programming in Scheme.

This package provides a library of procedures for formatting Scheme objects to text in various ways, and for easily concatenating, composing and extending these formatters efficiently without resorting to capturing and manipulating intermediate strings.

The Nanopass framework is an embedded domain-specific language for writing compilers composed of several simple passes that operate over well-defined intermediate languages. The goal of this organization is both to simplify the understanding of each pass, because it is responsible for a single task, and to simplify the addition of new passes anywhere in the compiler. Nanopass reduces the boilerplate required to create compilers, making them easier to understand and maintain.

This package provides a port of the MIT/GNU Scheme Scmutils program to Chez Scheme. The port consists of a set of libraries providing most of the functionality of the original.

Chez-sockets is an extensible sockets library for Chez Scheme.

The Nanopass framework is an embedded domain-specific language for writing compilers composed of several simple passes that operate over well-defined intermediate languages. The goal of this organization is both to simplify the understanding of each pass, because it is responsible for a single task, and to simplify the addition of new passes anywhere in the compiler. Nanopass reduces the boilerplate required to create compilers, making them easier to understand and maintain.

Chez Scheme is a self-hosting compiler: building it requires ``boot files'' containing the Scheme-implemented portions compiled for the current platform. (Chez can then cross-compile boot files for all other supported platforms.)

The Racket package cs-bootstrap (part of the main Racket Git repository) implements enough of a Chez Scheme simulation to load the Chez Scheme compiler purely from source into Racket and apply the compiler to itself, thus bootstrapping Chez Scheme. Bootstrapping takes about 10 times as long as using an existing Chez Scheme, but cs-bootstrap supports Racket 7.1 and later, including the Racket BC variant.