Gaussian Job File (GJF)
=======================

The Gaussian Job File (GJF) format is used to define computational jobs for Gaussian, a popular quantum 
chemistry software package. GJF files typically contain information about the molecular structure, 
computational methods, and other parameters necessary for performing quantum chemical calculations. 
Below is a simplified example of a GJF file for a molecular structure:

.. code-block:: bash

   #P B3LYP/6-31G(d) Opt

   Molecule Specification

   0 1
   O   0.00000   0.00000   0.00000
   H   0.75700   0.58600   0.00000
   H  -0.75700   0.58600   0.00000
   Tv  5.00000   0.00000   0.00000
   Tv  0.00000   5.00000   0.00000
   Tv  0.00000   0.00000   5.00000


In this example:

- The `#P B3LYP/6-31G(d) Opt` line specifies the computational method (B3LYP) and basis set (6-31G(d)) for optimization.
- The "Molecule Specification" section provides information about the molecular structure.
- `0 1` indicates that the molecule has a net charge of 0 and a spin multiplicity of 1 (singlet).
- Atom types (O, H) are followed by their Cartesian coordinates.
- The `Tv` lines indicate cell vectors in the x, y, and z directions.

This example represents a GJF file for a simple water molecule, where an optimization calculation is requested using the B3LYP functional and the 6-31G(d) basis set.

It's worth noting that GJF files can include additional specifications for different types of calculations, 
such as frequency calculations, single-point energy calculations, or electronic structure analyses. 
The specific contents of a GJF file may vary depending on the computational task and the desired level of theory.
Always consult the Gaussian documentation for the appropriate syntax and options for your specific calculations.