Tutorial:Getting started
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DIRAC uses two files as inputs: the input file
*.inp,
which determines what should be calculated, and the molecule file
*.mol or *.xyz ,
which defines the molecular geometry and possibly the basis set. These files are described in detail in the Manual.
When DIRAC runs it writes its output to a text file, named after the molecule and input file names.
If this file already exists, for example from a previous calculation,
the old file is renamed to make place for the new output.
The pam script that launches the main DIRAC executable also writes some general information to standard output.
Let's try it out and run our first DIRAC calculation with the following minimal input (dc_hf.inp) to calculate the Dirac-Coulomb Hartree-Fock ground state
**DIRAC .WAVE FUNCTION **WAVE FUNCTION .SCF *END OF INPUT
together with the following example molecule file (ch3f.mol):
DIRAC
CH3F - this line is a comment
this line is also a comment
C 3
6. 1
C 0.0 0.0 0.426596314746
LARGE BASIS cc-pVDZ
9. 1
F 0.0 0.0 -0.98392891998
LARGE BASIS cc-pVDZ
1. 3
H1 0.509715617414 0.882853346772 0.786416057331
H2 0.509715617414 -0.882853346772 0.786416057331
H3 -1.01943123483 0.0 0.786416057331
LARGE BASIS cc-pVDZ
FINISH
Now start the calculation by executing:
pam --mb=200 --mol=ch3f.mol --inp=dc_hf.inp
The --mb=200 flag specifies that DIRAC should allocate 200 MB for the work array. If everything works fine the results of the calculation will be written to dc_hf_ch3f.out. In addition an archive file dc_hf_ch3f.tgz will be created. Depending on the type of calculation the archive file may include:
- DFCOEF containing molecular orbital coefficients and possibly energies.
- *.cube containing plots of molecular properties, typically electron densities, in the gridded Gaussian Cube format.
- Additional files for restarting particular types of calculations.
