Gaussian 16W Reference

The Default.Rou Configuration File

Many default characteristics of Gaussian 16W may be specified in its configuration file, Default.Rou. This file is located in the main G16W directory; it is set up automatically for your system when the program is installed. If the system configuration changes—if you add more memory, for example—you will want to change it. You may want to add additional items.

Note: The file is called “Default.Route” on other operating systems. When you encounter this name in general Gaussian 16 documentation, know that Default.Rou is that you use under Windows.

Here are the contents of a Default.Rou file that might be installed on a computer with several gigabytes of memory and four
processors:

 -M- 512MB
 -P- 4

The first line specifies the maximum memory usage to be 512 MB (increasing it from the default of 256 MB). This value can be overridden for an individual job with the %Mem Link 0 command. Do not set this value to the total amount of memory in the system, since you will need to leave some available for Windows and other concurrent applications. However, if you increase the amount of memory on the system, you will need to increase this parameter to take advantage of it. The second line says to run jobs on four processors by default.

You may want to set additional options in the Default.Roufile. A very useful option to set is MaxDisk, which specifies the amount of available scratch space on the system (the defaul unit is again 8-byte words). Here is an example line which sets it to 40 GB:

 -#- MaxDisk=40GB

This option enables the use of density fitting sets wherever applicable and possible:

 -#- DensityFit 

In general, defaults for any applicable route section keywords may be set in the Default.Rou file.
These defaults may always be overridden by the route section of an individual job. See the Gaussian 16 User’s Reference for a full discussion of this configuration file and its possible options.

Last updated on: 14 August 2016.