Free computer software for physical chemistry

1. Linux - the best (and free) operating system for all computers.
    Fedora distribution,
    Ubuntu Linux distribution,
    Debian Linux distribution,
    and many others.

2. TeX and LaTeX - the ultimate word processor.
    In Fedora, install with yum (tetex package).
    In Ubuntu and Debian, install with apt-get (tetex package).
    Mac users can obtain MacTeX. It is also available from Fink (tetex package).
    Other Linux versions or Windows users should download TeX Live. (Note: tetex is no longer maintained!)

3. Maxima (Linux, Mac, Windows) - a symbolic algebra package.
    Program homepage:
    Direct link to download page for Linux and Windows.
    Mac users have to install Fink first and get Maxima from there. Note that Fink requires you to install the software developer kit.
    Note that many Linux distributions have their own repositories where Maxima is available
    (e.g. yum in Fedora and apt-get in Debian based systems).
    A simple graphical frontend is also available (xmaxima).

4. Wxmaxima (Linux, Mac, Windows) - a graphical frontend for Maxima.
    Program homepage:
    Binary and source packages available for Linux and Windows.
    Mac users have to install Fink and get wxmaxima from there.

5. Octave - a program for high-level numerical computations.
    Program homepage:
    A direct link to download page (Linux, Mac, Windows).

6. Grace - a good program for producing 2-D plots and fitting data.
    Program homepage:
    Available for Linux (with yum for Fedora and apt-get for Ubuntu and Debian) and Mac (with fink).
    Not available for Windows.

7. OpenDX - data visualization package (2-D and 3-D).
    Program homepage:
    Linux version is freely available through yum (Fedora) and apt-get (Ubuntu and Debian).
    Source code is also available from the program homepage.