# Parse linked frequency calculations with cclib

I have multiple Q-Chem output files for TS search starting and finishing with frequency calculations (two sets of calculated IR data in total). To parse and plot spectra I use cclib and a script discussed recently. But when cclib parses output, it combines both frequency calculations. Is there a way to parse only one (the second) selectively?

• I edited this to mean you are doing a linked calculation separated by an @@@ correct? If not you can revert my edit May 21 '20 at 7:05
• Right, @CodyAldaz! May 21 '20 at 7:20
• Hi @DmitryEremin, this sounds like a bug. It would be helpful to show us what you mean by "combining both frequency calculations." Ultimately, you can always file an issue on GitHub. May 21 '20 at 12:03
• Here is what I have: In the first Job I calculate Frequencies to get Hessian for further TS search. As a result in a selected example I got i1100 and i15. After TS search I run a second Frequencies calculation and got i250. When I parsed IR frequencies with CClib and plotted the data I got all three imaginary frequencies on the graph. May 21 '20 at 16:36

I think the easiest way to parse multiple-job files from Q-Chem is if you just manually split the output file into the parts that pertain to the individual jobs. Just locate where the first job ends and the second one starts and save the output in individual files. If you have lots of those jobs to split, then I am sure this could be done with the head and tail commands.