How do I run Gaussian ?

Please note: The FAQ pages at the HPCVL website are continuously being revised. Some pages might pertain to an older configuration of the system. Please let us know if you encounter problems or inaccuracies, and we will correct the entries.

To run Gaussian on HPCVL clusters, you have to belong to a user group "g98"(it's called that for historical reason, but it applies to all versions of Gaussian). You will be entered into the group list when you have read our license agreement and signed a statement that you have done so.

Given the complexity of the underlying methods, Gaussian is very simple to use. A given calculation is performed by preparing an input file, piping it to the standard input of the program g09, and catching the standard output in a log-file. We suggest you use the "extension" .g09 for input files and .log for the results.

Interactively, the command line to invoke Gaussian is thus:

g09 < test.g09 >test.gout &

The ampersand & submits the job into the background, so it doesn't block your terminal. This will only work if you are a member of the g98 group and have set the environment correctly (see previous question). Note that the interactive execution of Gaussian is only meant for test runs.

Gaussian input files have to be set up according to a scheme that is explained in the "User's Reference". It is impossible to give an outline here. The program uses the concept of keywords to describe the method used, the molecule to be described, and the conditions for the calculation (such as basis sets). Sample files can be found in opt/gaussian/g09/bsd/logs.

Note that it is absolutely essential to have a good idea about the size and complexity of your calculations before you start a Gaussian job. Many of the methods mentioned above have terrible scaling properties, i.e. the computational cost grows very quickly with the number of electrons, degrees of freedom, or number of basis functions used. We suggest you start with a small basis set and a cheap method, and then slowly increase those parameters.