Quantumbiochemistry.org

If you want to do quantum chemical calculations then you have to install the proper software. Because the calculations are way too elaborate to be done manually.

With quantum chemical software we mean software that can calculate a numerical solution for the electronic wave function of a molecule. This software is very CPU intensive and depending on the model the calculation can take day, weeks, months to finish a calculation. I use a dedicated computer to do the calculations.

Additionally you will probably want to visualise the molecules and the results of the quantum calculations. And for reporting you will need at least a spreadsheet and maybe you can write some of your own software.

Writing your own software can take a lot of time. If you plan to do serious research that I advise you to look at more advanced software systems like the Wolfram Language They are not free of charge but can make you save a lot of time.

Currently only GAMESS can be obtained free of charge. The software is provided by Mark Gordon's Quantum Theory Group. There is a version available for windows that is easy to install and easy to use. Check out the website at http://www.msg.ameslab.gov/ for all info related to download, installation and use of their software.

A list of other software systems that can be used for quantum chemistry is available on wikipedia

You probably need some software to view molecules in 3 dimensions. There are several molecular modelling software systems available, some of them expensive. A popular software is Avogadro. We use Avogadro a free and open source software. We also use MacMolPlt a freeware software.