Crate chemfiles [] [src]

Chemfiles is a multi-language library written in modern C++ for reading and writing from and to molecular trajectory files. These files are created by your favorite theoretical chemistry program, and contains informations about atomic or residues names and positions. Some format also have additional informations, such as velocities, forces, energy, …

This crate expose the C API of chemfiles to Rust, and make all the functionalities accessibles. For more informations on the C++ library, please see its documentation. Specifically, the following pages are worth reading:

As all the function call the underlying C library, they all can fail and thus all return a Result<_, Error> value.



An Atom is a particle in the current Frame. It stores the following atomic properties:


Error type for Chemfiles.


A Frame contains data from one simulation step: the current unit cell, the topology, the positions, and the velocities of the particles in the system. If some information is missing (topology or velocity or unit cell), the corresponding data is filled with a default value.


A Match is a set of atomic indexes matching a given selection. It should be used like a &[u64].


A Residue is a group of atoms belonging to the same logical unit. They can be small molecules, amino-acids in a protein, monomers in polymers, etc.


A Selection allow to select atoms in a Frame, from a selection language. The selection language is built by combining basic operations. Each basic operation follows the <selector>[(<variable>)] <operator> <value> structure, where <operator> is a comparison operator in == != < <= > >=.


A Topology contains the definition of all the atoms in the system, and the liaisons between the atoms (bonds, angles, dihedrals, ...). It will also contain all the residues information if it is available.


The Trajectory type is the main entry point when using chemfiles. A Trajectory behave a bit like a file, allowing to read and/or write Frame.


An UnitCell represent the box containing the atoms, and its periodicity.



Available unit cell shapes.


Possible causes of error in chemfiles



Use callback for every chemfiles warning. The callback will be passed the warning message.


Get the version of the chemfiles library.

Type Definitions


Custom result type for working with errors in chemfiles