The following is a typical Gaussian input file for a somewhat more demanding calculation, taking a CCSD(T)/6-311+G(d,p) sp on formaldehyde as an example:
%rwf=/scr1/zipse/z1,1990MB,/scr1/zipse/z2,1990MB,/scr1/zipse/z3,1990MB,/scr1/zipse/z4,1990MB %nosave %nproc=1 %mem=256MB %chk=/scr1/zipse/test1.chk #P CCSD(T)/6-311+G(d,p) scf=tight test1 CCSD(T)/6-311+G(d,p) sp formaldehyde 0 1 C1 O2 1 r2 H3 1 r3 2 a3 H4 1 r4 2 a4 3 d4 r2=1.20 r3=1.0 r4=1.0 a3=120. a4=120. d4=180.
The first line of the input file:
specifies the names of a series of temporary (read/write) files together with their maximum size. These files should be located on the compute node in a locally available file system (here: /scr1/zipse). The maximum size of each of the rwf files on a 32-bit system is 2 GB, while it is limited by the disk size on 64-bit systems (currently 200 GB). On these latter systems the first line can thus be replaced by specifying one single rwf file of sufficient size:
The following line:
tells the program to delete these files after successful completion of the calculation. The number of processors to be used for a particular calculation is specified by the line:
The number defaults to nproc=1 (one processors) if not given otherwise. The main memory available for the calculation is specified by the line:
The default value (if nothing is specified) amounts to 6000000 words (or 48MB). Information on the structure as well as the wavefunction of the system under study are permanently stored in the checkpoint file, named here explicitly:
If no file name is supplied in the input file, the checkpoint files are generated during program execution, but deleted on successful termination of the program. The remainder of the input file describes, after a line of keywords, an empty line, a comment line, another empty line, and finally the specification of charge (here: 0) and multiplicity (here: 1 for a singlet) the structure of the system.