# What are the output files generated by an NEB calculation?

I just used Orca for the first time. Can someone address me a valid guide to understand all the files in the directory?

I'd like to perform a Nudged Elastic Band (NEB) calculation, but I'm stuck understanding the output file of the preliminary optimisation of the starting and ending structures.

• You may need to clarify the question somewhat. I'm not a regular Orca user, but it seems like almost everything Orca does is uses temporary files in someway and which ones remain as output (or get deleted) depends on your calculation settings (e.g. print settings, geometry optimization vs frequency vs response properties, etc). It may help if you narrow down the question to some specific problem you are having with interpreting a calculations output. The orca manual is probably the easiest place to look for general info on Orca.
– Tyberius
Feb 11 at 19:43
• The number and types of files depend on the job type, and enumerating all output files for all possible job types is almost impossible. Are you doing a ground state single point calculation, a ground state geometry optimization calculation, a ground state frequency calculation, a TDDFT single point calculation, or some other kind of calculation? This helps us to narrow down the scope of the question. Even better if you can give a screenshot of the actual files that you see Feb 12 at 9:37
• @wzkchem5 I edited the post Feb 12 at 10:17

This question is bit too broad for a specific answer. The most common types of files that are generated by Orca are:

1. *.gbw files are binary wavefunction files, they cannot be read by a text editor, only by Orca. They also may contain basis set information and geometry information
2. *.engrad files contain energy and gradient, generated in an !ENGRAD run or !OPT run.
3. *_property.txt are text files containing various properties that has been calculated in the run
4. *.hess files contain the Hessian (i.e. second derivative matrix) data
5. *.cis files are generated during CIS or TD-DFT runs, and likely contains data about excited states
6. *.smd.out are text files, and they contain information about the solvation energy contributions and surface areas when SMD solvation is used

There are also temporary files generated during the run, usually with extensions *.tmp, *.0, *.1, *.VAUXJ etc. which are deleted when the run ends.

Edit: The question is specifically about NEB calculation. These files are generated by a standard NEB-TS run with preliminary optimization of the end points:

1. file.NEB.log - This is a plain text log file that contains the energies, forces, and various other quantities of each image in the NEB calculation, for each iteration.
2. file_reactant.xyz - This contains the optimized structure of the reactant (after the optimization ends)
3. file_reactant_trj.xyz - This is the optimization trajectory for the reactant.
4. file_product.xyz - Optimized structure of product
5. file_produc_trj.xyz - Optimization trajectory of product
6. .gbw, .opt, .prop, .densities files associated with the product and the reactant
7. file_im{n}.xyz - These contain the current structures of the images ($$n$$th image) and are updated as the NEB calculation progresses. (For some reason Orca seems to delete these files on my laptop after the calculation ends)
8. file_im{n}.gbw - These contain the wavefunctions of each image
9. file.interp - This file contains the energy profiles and interpolations during each iteration. The data for final iteration is stored in file.final.interp
10. file_NEB-CI_converged.xyz - The final converged structure of the climbing image
11. file_NEB-TS_converged.xyz - The final converged structure of the TS
12. file_initial_path_trj.xyz - The first NEB path constructed

A description of the files is also given inside the Orca output:

Following output files will be written:
Energy profile during opt. written to    ....  NEB-test.interp
Optimization log-file                    ....  NEB-test.NEB.log
Current trajectory will be written to    ....  NEB-test_MEP_trj.xyz
and to allxyz file                ....  NEB-test_MEP.allxyz
and individual images to xyz file ....  NEB-test_im{NIm}.xyz
Trajectory history will be written to    ....  NEB-test_MEP_ALL_trj.xyz
Converged CI will be written to          ....  NEB-test_NEB-CI_converged.xyz
Converged TS will be written to          ....  NEB-test_NEB-TS_converged.xyz