Gaussian 03 Online Manual
Last update: 10 October 2003

This section lists all Link 0 commands, which are optional and precede the route section if present. See this page for a more detailed discussion of the scratch file naming commands.

Link 0 commands may be up to 500 characters in length.

%Mem=N
Sets the amount of dynamic memory used to N words (8N bytes). The default is 6MW. N may be optionally followed by a units designation: KB, MB, GB, KW, MB or GW.

%Chk=file
Locates and names the checkpoint file.

%RWF=file
Locates and names a single, unified Read-Write file (old-style syntax).

%RWF=loc1,size1,loc2,size2, ...
An alternate syntax is provided for splitting the Read-Write file among two or more disks (or file systems). Each location is followed by a maximum size for the file segment at that location. The default units for each size is words; the value may be optionally followed by KB, MB, GB, KW, MW or GW (with no intervening spaces) to indicate units. A value of -1 for any size parameter indicates that any and all available space may be used, and a value of 0 indicates that an existing segment should retain its current size. The locations may be either directory locations, or full pathnames. Note that directory specifications must include terminal slashes (on UNIX systems).

%Int=spec
Locates and names the two-electron integral file(s). spec may take on either of the forms used for the Read-Write file (described above).

%D2E=spec
Locates and names the two-electron integral derivative file(s). spec may take on either of the forms used for the Read-Write file (described above).

%KJob LN [M]
Tells the program to stop the run after the M^th occurrence of Link N. For example, %KJob L502 2 will cause the run to terminate after Link 502 has been run for the second time. M may be omitted; it defaults to 1.

%NProcLinda=N
Requests that the job use up to N processors for distributed memory parallel execution. This capability is only available on some computer systems, and Gaussian must have been built with parallel processing enabled. On parallel machines, the number of processors to use in production runs is usually set in the Default.Route file, and the %NProcLinda Link 0 command is used to override this local default (e.g., to run debug jobs on a single processor even if the default is to use 4 processors). If %NProcLinda is not used, and no default is provided in the Default.Route file, then one processor is used. Note: the %NProc directive used in earlier program versions is obsolete.

%NProcShared=N

Requests that the job use up to N processors for shared memory parallel execution on SMP multiprocessor computers. This capability is only available on some computer systems, and Gaussian must have been built with parallel processing enabled. On parallel machines, the number of processors to use in production runs is usually set in the Default.Route file, and the %NProcShared Link 0 command is used to override this local default (e.g., to run debug jobs on a single processor even if the default is to use 4 processors). If %NProcShared is not used, and no default is provided in the Default.Route file, then one processor is used.

%Save
Causes Link 0 to save scratch files at the end of the run. By default, all non-specified scratch files are deleted and all named scratch files are saved when the run completes successfully.

%NoSave
Causes Link 0 to delete scratch files at the end of a run, including any files that were named explicitly following this directive. In other words, if a file is named before %NoSave is encountered, it will not be saved. However, if the % directive naming the file appears after the %NoSave directive, the file will be retained.

For example, these commands specify a name for the checkpoint file, and an alternate name and directory location for the read-write file, and cause only the checkpoint file to be saved at the conclusion of the Gaussian job:

%RWF=/chem/scratch2/water     Files to be deleted go here. 
%NoSave       
%Chk=water                    Files to be saved go here. 

If both %Save and %NoSave are specified, then the one appearing latest in the input file takes precedence.

%Subst LN dir
Tells Link 0 to take the executable (.exe file) for a link from an alternate directory. For example %SUBST L913 /user/chem will cause /user/chem/l913.exe to be run instead of the default executable (in $g03root). The directory specification should be in the usual format for the machine involved. Only the directory can be specified; the file name must have the standard form of lnnnn.exe, where nnnn is the Link number.