Skip to content

ReaxFF Output Files Reference

This directory documents the output files generated by ReaxFF during molecular mechanics (MM), molecular dynamics (MD), and force-field (FF) optimization runs.

The table below summarizes the most common output files, the type of run in which they appear, and their purpose. Detailed explanations for the more complex files are provided in the accompanying markdown documents in this directory.

Overview of ReaxFF Output Files

File name Related to Description
NAME.bgf All runs Output geometry in .bgf format
NAME.geo All runs Output geometry in .geo format
output.pdf MM / MD runs Output geometry in PDF format
output.MOP MM / MD runs Output Z-matrix in MOPAC format
xmolout All runs Trajectory file in XYZ format
moldyn.vel MD runs Restart file (see vels file documentation)
molsav.#### MD runs Restart file, controlled by iout6
moldyn.#### MD runs Trajectory files, controlled by iout2
fort.7 All runs Connection table using cutof3 bond-order cutoff
fort.8 All runs Connection table including partial charges
fort.13 FF optimization Total force-field error
fort.24 FF optimization Heat increment values (iincop = 1)
fort.40 All runs Forces (icheck > 0)
fort.41–fort.50 All runs Partial forces (icheck > 0)
fort.56 MM / MD runs ReaxFF charge distribution
fort.57 MM runs Energy minimization report
fort.58 MM runs Partial energy contribution report
fort.59 MD runs NPT pressure report
fort.65 All runs Debug output (idebug = 1)
fort.71 MD runs Energy, temperature, and pressure report
fort.73 MD runs Partial energy contribution report
fort.74 All runs Heat of formation and volume
fort.76 Restraint runs Restraint report
fort.79 FF optimization Parabolic extrapolation report
fort.83 FF optimization Force-field files from optimization
fort.90 MM / MD runs .bgf output
fort.91 MM / MD runs Z-matrix output
fort.98 MM / MD runs .geo output
fort.99 FF optimization Detailed cost-function report

Notes

  • NAME refers to the structure identifier defined in the DESCRP field of the input geometry.
  • #### indicates the iteration number, typically controlled by iout2 or iout6.
  • Control keywords such as iout1, iout2, iout6, cutof2, cutof3, icheck, and idebug are defined in the control file.

How to Use This Directory

  • Files that are format-identical to input files (e.g. .geo, .bgf) are not re-documented in detail.
  • Files with complex structure or diagnostic value (e.g. fort.7, fort.71, fort.73, fort.99) have dedicated markdown files in this folder.
  • This reference is intended to support both raw ReaxFF users and ReaxKit analysis workflows.

If you are using ReaxKit, many of these files are parsed automatically by dedicated handlers and analyzers.