This section discusses the general procedures for installing and configuring Gaussian on UNIX systems. Be sure to check the instructions and release notes accompanying your version of the program for additional or alternate instructions pertaining to your particular computer system.
The Gaussian directories will require about 1.5 - 2 GB of disk space for the executables, depending on the computer system.
The default memory allocation in Gaussian 09 is 256 MB. The large fixed dimensions in the program necessitate a swap space size of 1-2 GB. Of course, additional swap space will be required if more memory is requested in a job by using the %Mem Link 0 command, or via the -M- command in the Default.Route file. These requirements are for each simultaneously executing job.
Refer to the platform list which comes with the CD. The most recent version of this document can always be found at www.gaussian.com/g09_plat.htm.
Gaussian locates executables and creates scratch files in directories specified by several environment variables. However, the user is responsible for creating two of them:
g09root : Indicates the directory where the g09 directory resides (i.e., the directory above it).
GAUSS_SCRDIR : Indicates the directory which should be used for scratch files.
The Gaussian initialization files are responsible for initializing other aliases and environment variables as needed. All Gaussian users need to execute the appropriate Gaussian initialization file within their UNIX shell-specific initialization file. See chapter 2 for more details.
The environment variables created by g09.login and g09.profile include:
GAUSS_EXEDIR : Specifies the directories in which the Gaussian images are stored. By default it includes the main directory $g09root/g09 and several alternate directories.
GAUSS_ARCHDIR : Specifies the directory in which the main site-wide archive file is kept, and into which temporary archive files should be placed if the main archive is unavailable. It defaults to $g09root/g09/arch if unset.
G09BASIS : The directory which contains files specifying the standard Gaussian internally stored basis sets, as well as some additional basis sets in the form of general basis set input. This environment variable is provided for convenience and is designed for use with the @ include mechanism.
Network/cluster parallel calculations using Linda may also use the GAUSS_LFLAGS environment variable to pass options to the Linda process. See the discussion of running Gaussian jobs with Linda for details.
On UNIX systems, Gaussian generates unique scratch file names based on the process ID when no name has been specified by the user. This mechanism is designed to allow multiple Gaussian jobs to execute simultaneously using a common scratch directory.
Scratch files are deleted automatically when a job completes successfully or dies cleanly by default. However, scratch files are not deleted when a job is killed externally or otherwise terminates abnormally. Consequently, leftover files may accumulate in the scratch directory.
An easy method for avoiding excessive clutter is to have all users share a common scratch directory, and to have that scratch directory cleared at system boot time by adding an rm command to the appropriate system boot script (e.g., /etc/rc or one of the files under /etc/rc.d/rc3.d). If the NQS batch system is in use, clearing the scratch directory should also be done before NQS is started, ensuring that no jobs are using the directory when it is cleared.
Last update: 23 April 2013