Link 0–Default.Route–Command Line Option–Env. Variable Equivalencies

Most options that control how Gaussian 16 operates can be specified in any of 4 ways. From highest to lowest precedence these are:

  1. As Link 0 input (%-lines): This is the usual method to control a specific job and the only way to control a specific step within a multi-step input file. Example: %CPU=1,2,3,4
  2. As options on the command line: Command line options are useful when you want to define aliases or other shortcuts for different common ways of running the program. Example: g16 -c="1,2,3,4" …
  3. As environment variables: This is most useful in standard scripts, for example for generating and submitting jobs to batch queuing systems. Example: export GAUSS_CDEF="1,2,3,4"
  4. As directives in the Default.Route file: This is most useful when one wants to change the program defaults for all jobs. Example: -C- 1,2,3,4

When searching for a Default.Route file the current default directory is checked first, followed by the directories in the path for Gaussian 16 executables: environment variable GAUSS_EXEDIR, which normally points to $g16root/g16.

The following table lists the equivalences among Link 0 commands, command line options, Default.Route items and environment variables. The -h, -o options and the -i and -o option classes were introduced in [REV B], as were their corresponding environment variables.

Default.Route Link 0 Option Env. Var. Description
Gaussian 16 execution defaults
-R-   -r GAUSS_RDEF Route section keyword list.
-M- %Mem -m GAUSS_MDEF Memory amount for Gaussian jobs.
-C- %CPU -c GAUSS_CDEF Processor/core list for multiprocessor parallel jobs.
-G- %GPUCPU -g GAUSS_GDEF GPUs=Cores list for GPU parallel jobs.
-S- %SSH=command -s GAUSS_SDEF Program to start workers for network parallel jobs. %UseSSH is equivalent to %SSH=ssh and %UseRSH similarly specifies rsh.
-W- %LindaWorkers -w GAUSS_WDEF List of hostnames for network parallel jobs.
-P- %NProcShared -p GAUSS_PDEF #processors/cores for multiprocessor parallel jobs.
Deprecated; use -C-.
-L- %NProcLinda -l GAUSS_LDEF #nodes for network parallel jobs. Deprecated; use -W-.
Archive entry data
-H-   -h GAUSS_HDEF Computer hostname.
-O- -o GAUSS_ODEF Organization (site) name.
Utility program defaults
-F-     GAUSS_FDEF Options for the formchk utility.
-U-     GAUSS_UDEF Memory amount for utilities.
Parameters for scripts and external programs
# section -x GAUSS_XDEF Complete route for the job (route not read from input file).
%Chk -y GAUSS_YDEF Checkpoint file for job.
%RWF -z GAUSS_ZDEF Read-write file for job.
%OldChk -ic GAUSS_ICDEF Existing checkpoint file from which to read input.
%OldMatrix -im GAUSS_IMDEF Matrix element file from which to read input.
%OldMatrix=(file,i4lab) -im4 GAUSS_IM4DEF Matrix element file using 4-byte integers from which to read input.
%OldMatrix=(file,i8lab) -im8 GAUSS_IM8DEF Matrix element file using 8-byte integers from which to read input.
%OldRaw -ir GAUSS_IRDEF Raw matrix element file from which to read input.
%OldRaw=(file,i4lab) -ir4 GAUSS_IR4DEF Raw matrix element file using 4-byte integers from which to read input.
%OldRaw=(file,i8lab) -ir8 GAUSS_IR8DEF Raw matrix element file using 8-byte integers from which to read input.
  -oc GAUSS_OCDEF Output checkpoint file. Generally redundant with -y/GAUSS_YDEF.
  -om GAUSS_OMDEF Output matrix element file.
  -om4 GAUSS_OM4DEF Output matrix element file using 4-byte integers.
  -om8 GAUSS_OM8DEF Output matrix element file using 8-byte integers.
  -or GAUSS_ORDEF Output raw matrix element file.
  -or4 GAUSS_OR4DEF Output raw matrix element file using 4-byte integers.
  -or8 GAUSS_OR8DEF Output raw matrix element file using 8-byte integers.

Note that the quotation marks are normally required around the specified value for the command line and environment variables to avoid modification of the parameter string by the shell.