Example I: Total energy of S2 dimer using local basis DFT method.

INPUT FILE COMMENTS
echo The first directive “echo” is optional but highly recommended. Its purpose is to write out the contents of your input file into the output file.

scratch_dir ./scratch
The location scratch directory. The scratch directory contains temporary files that may be discarded after the calculation is complete.
permanent_dir ./perm
The location of permanent directory The permanent directory contains essential files which will be required should you wish to restart your calculation.
title "S2 local basis DFT" The “title” directive is also optional. You might want to put a short sentence identifying the nature of your calculation
start s2 The "start" directive signifies that this is a new calculation. The string ( "s2" in this case ) sets up a prefix for permanent files (e.g. database file ) that will be associated with this calculation. You will need those files if you want to restart your calculation.

geometry
S 0.0 0.0 0.0
S 0.0 0.0 1.95
end

The geometry block specifies the name of the elements that comprise your system as well as their coordinates in the following format:

Name1 x1 y1 z1
Name2 x2 y2 z2

……

Unless indicated otherwise, the default units are angstroms, and the system will be centered around the origin.

basis "ao basis"

* library "6-31++G**"

end

Basis block sets up local basis assignments for the elements in the system. This can be done on element-by-element basis or all at once using "star" notation. Here we are using 6-31++G** basis set
task dft energy Task directive requests the actual calculation. In this case we are using local basis DFT method (keyword dft) and requesting total energy calculation ( keyword energy)