| 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 | 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 …… 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) |