Commercial (centrally provided by IT shop).
The use of Gaussian is subject to the following conditions (this is just a summary; the license agreement is several pages long):
Warning -- This program may not be used in any manner that competes with the business of Gaussian, Inc. or will provide assistance to any competitor of Gaussian, Inc. The licensee of this program is prohibited from giving any competitor of Gaussian, Inc. access to this program. By using this program, the user acknowledges that Gaussian, Inc. is engaged in the business of creating and licensing software in the field of computational chemistry and represents and warrants to the licensee that it is not a competitor of Gaussian, Inc. and that it will not use this program in any manner prohibited above.
If you want to use Gaussian, simply send a note to Cluster Support stating that you accept these conditions.