What I need is a script that will: 1. Create input files 2. Run qchem jobs 3. Parse output 4. Plot the data The input files will consider Atom 1 and Atom 2. We will also consider the atomic radii r_min and r_max and need information on delta_r. Concerning the r values, the script should read in arguments, re-print arguments, and print a list of the r's.

I would start by asking questions about my needs and address them one by one. Your input files:

• Where do they come from? Data input by the user in a form? Data selected by the user from a form? And what format is required by qchem as input?
• What will be required to run the qchem job? A list of the input files? How might it get that list? How do I use Perl to start the job and give it the list of files? etc...
• Where does this list of 'radii' come from? Read in from where...user input or already known values stored somewhere? etc....

Take each of the questions you have and find a way to do it in Perl. Write yourself a script that does just enough to prove you have the concept down, then move on to the next question/piece. By the time you get done, you will probably have a lot better idea of what scripting in general means and how it is approached in Perl. As you go along, you will probably have questions that you can ask here.

Some of the answers you get will refer to Perl Modules from CPAN which can in some cases make your work less cumbersome by leveraging other peoples work. I would not worry about that to start. Just take your first question and learn about how you might come up with an answer. That is how I learned to write Perl code. Once you get going, the concepts come faster and faster.

Hope that is encouraging, and maybe a bit helpful too.