Fityk is nonlinear curve-fitting and data analysis software. It allows data visualization, separation of overlapping peaks, and least squares fitting using standard Levenberg-Marquardt algorithm, a genetic algorithm, or Nelder-Mead simplex method. It knows about many functions (mostly bell-shaped, like Gaussian, Loretzian, Pearson 7, Voigt, Pseudo-Voigt, and Doniach-Sunjic) and user-defined functions can be easily added. It also enables background subtracting, data calibration, and task automation with a simple script language. It is mainly used to analyze powder diffraction patterns, chromatography, photoluminescence, infrared, and Raman spectroscopy, but it can be used to fit analytical functions to any kind of data.
The Gnome Chemistry Utils includes the following programs: a 2D chemical editor (GChemPaint), a chemical calculator (computes raw formule, molar weight, mass composition, and isotopic pattern), a 3D molecule viewer using OpenGL to display molecular models, a crystal structure viewer and editor, a spectrum viewer, and a periodic table of the elements.
GAMGI (General Atomistic Modelling Graphic Interface) is a program to build, view, and analyze atomic strucures such as molecules, crystals, glasses, liquids, etc. It aims to be useful for: the scientific community working in Atomistic Modelling that needs a graphic interface to build input data and to view and analyse output data, calculated with Ab-Initio and Molecular Mechanics programs; the scientific community at large studying chemistry, physics, materials science, geology, etc., that needs a graphic interface to view and analyse atomic structural information and to prepare images for presentations in classes and seminars; teaching chemistry and physics in secondary schools and universities; science promotion in schools, exhibitions and science museums.
The massXpert software package is a mass spectrometry environment for linear (bio-)polymers. It inherits all the innovations of GNU polyxmass. It allows the detailed definition of new polymer chemistries in the XpertDef module. These chemistry definitions are then used in the desktop calculator-like mass calculator (XpertCalc) and in the sophisticated polymer sequence editor and (bio-)chemical/mass spectrometric simulations module (XpertEdit). Available simulations include polymer and monomer chemical modifications, polymer sequence cleavage, gas-phase fragmentation, m/z ratio calculations, and more.
Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
BioJava aims to provide a comprehensive set of Java components for the rapid development of applications in Bioinformatics. It contains interfaces for representing Sequences, Features, and other important bioinformatics concepts. It can also read and write sequence data in a variety of common formats and communicate with Ensembl databases and with DAS and BioCorba servers.
Cactus is a general, modular, parallel environment for solving systems of partial differential equations. The code has been developed over many years by a large international collaboration of numerical relativity and computational science research groups and can be used to provide a portable platform for solving any system of partial differential equations.
Ghemical is a molecular modelling software package with some nice 3D visualization tools. It supports methods based on both molecular mechanics and quantum mechanics (using MOPAC7, and MPQC for QM). The geometry optimization (for MM and QM) and molecular dynamics (for MM) algorithms are included. Ghemical is written in C++, and hopefully offers a good framework for a generic freeware molecular modelling tool.