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Hello world

As a first example, we will take a sodium atom. With your favourite text editor, create the file inp .

 CalculationMode = gs
 %Coordinates
     'Na' | 0.0 | 0.0 | 0.0
 %

 Radius = 10.0
 Spacing = 0.5

This input file should be essentially self-explanatory.

Note that when a species is not specified in the Species block, octopus reads the information of pseudopotentials from the defaults file (located under PREFIX/share/octopus/PP/ . The variables Radius and Spacing always have to be specified. There are no default values, in order to make sure that the convergence with respect to these is tested properly (see the tutorial on total energy convergence).

Then run octopus – for example, do


octopus > out
so that the output is stored in out file. If everything goes OK, out should look like:

Expand for full output

Take now a look at the working directory. Besides the initial file (inp ) and the out file, three new directories appear. In static/ , you will find the file info , with information about the static calculation (it should be hopefully self-explanatory, otherwise please complain to the authors…). In restart/ , you will find the gs directory that contains restart information about the ground-state, which is used if, for example, you want to start a time-dependent calculation afterwards. Finally, the exec directory has information about the run of octopus; inside the parser.log contains all the input variables parsed by octopus.

Exercises