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fort.58 file — MM partial energy decomposition

The fort.58 file contains a partial energy breakdown from a molecular mechanics (MM) energy minimization in ReaxFF.

It complements the total-energy report in fort.57 by decomposing the potential energy into individual physical contributions (bonding, angles, van der Waals, Coulomb, etc.).

Purpose of the fort.58 file

The fort.58 output is used to:

  • Analyze which interaction terms dominate the energy
  • Diagnose problematic force-field components
  • Understand convergence behavior during MM minimization
  • Support force-field development and debugging

When fort.58 is generated

  • Generated during MM energy minimization
  • Written once per MM iteration
  • Corresponds directly to iterations reported in fort.57
  • May be removed automatically if iout5 = 1 in the control file

File structure

The file consists of:

  1. A structure identifier
  2. A header line listing energy components
  3. One line per MM iteration with partial energies

Energy components

Each iteration reports the following energy terms (in kcal/mol):

Column Description
Eatom Over- and undercoordination energy
Elopa Lone-pair energy
Ebond Bond energy
Emol Molecular energy (not used in current force fields)
Eval Valence angle energy
Ecoa Valence angle conjugation energy
Ehb Hydrogen bond energy
Etor Torsion angle energy
Econj Torsion conjugation energy
Evdw van der Waals energy
Ecoul Coulomb (electrostatic) energy

Example 3.4: fort.58 output file

Ethyl_radical

Iter. Eatom Elopa Ebond Emol Eval Ecoa Ehb Etor Econj Evdw Ecoul

0 -6.922 0.000 -907.050 0.000 0.237 0.000 0.000 4.715 -0.508 257.018 -22.970
1 -6.741 0.000 -907.442 0.000 0.244 0.000 0.000 4.801 -0.512 257.123 -22.966
2 -6.559 0.000 -908.118 0.000 0.242 0.000 0.000 4.876 -0.516 257.524 -22.965
3 -6.196 0.000 -909.827 0.000 0.233 0.000 0.000 5.013 -0.523 258.720 -22.972
4 -6.283 0.000 -910.220 0.000 0.230 0.000 0.000 4.954 -0.521 259.253 -22.985
5 -6.305 0.000 -910.733 0.000 0.234 0.000 0.000 4.924 -0.520 259.819 -22.996
6 -6.340 0.000 -911.121 0.000 0.234 0.000 0.000 4.896 -0.519 260.277 -23.006

Relationship to fort.57

  • fort.57 reports the total potential energy (Epot) and convergence metrics
  • fort.58 reports partial energy components
  • The sum of energies in fort.58 does not equal Epot in fort.57

Why the totals differ

The energy required to generate atomic charges (Echarge) is not included in fort.58.

This missing contribution is reported separately in: - fort.73 / energylog

As a result:

Σ(Energies in fort.58) ≠ Epot (fort.57)

Practical notes

  • Large changes in a single term (e.g. Ebond or Evdw) often indicate the source of instability
  • Useful for tuning force-field parameters during optimization
  • Frequently parsed together with fort.57 in automated workflows

Summary

  • fort.58 provides a decomposed MM energy report
  • Written during MM minimization
  • Complements fort.57 but does not include charge-generation energy
  • Essential for detailed force-field diagnostics