ReaxFF Engine Features Vs. Old Standalone Program

Introduction

Starting with AMS2018, ReaxFF is an engine for the AMS driver, thus sharing many of the features and input syntax with the other engines in the Amsterdam Modeling Suite.

Before AMS2018, ReaxFF was run as a standalone program. The older standalone program (“Old ReaxFF”) can still be run from the command-line, also in AMS2020. Some features are only available in this older program.

See also

Old Standalone ReaxFF manual

The engine shares all core routines with the standalone program, guaranteeing identical energies and forces between these two codes.

Feature comparison

Some features of the old standalone ReaxFF program have been implemented into the AMS driver, others into the ReaxFF engine, and some are currently not available in the new implementation. The table below indicates how certain features can be activated.

Feature	New implementation	Old implementation
0D, 1D, 2D periodicity	AMS driver	not available
ACKS2	force field file	old manual entry
Adsorption analysis	AMS driver	old manual entry
Bond boost	AMS driver	old manual entry
ChemTraYzer	AMS utilities	old manual entry
CMAES FF optimizer	ParAMS	old manual entry
CVHD	AMS driver	old manual entry
Elastic wall restraint	not available	old manual entry
eReaxFF	force field file	old manual entry
External electric fields	AMS driver	old manual entry
Force-bias Monte Carlo	AMS driver	old manual entry
Force field parametrization	ParAMS	old manual entry
Grand-canonical Monte Carlo	AMS driver	old manual entry
Local atomic temperature	not available	old manual entry
LG dispersion	force field file	old manual entry
Molecular charge constraints	ReaxFF Engine	old manual entry
Molecule gun	AMS driver	old manual entry
NEMD (thermal conductivity)	AMS driver	old manual entry
Per-atom stress tensor	ReaxFF engine	old manual entry
Tapered bond orders	ReaxFF engine	old manual entry
Temperature profile along axis	AMS driver	old manual entry
Volume regimes	AMS driver	vregime.in Training Course

Differences in execution

To run ReaxFF as an AMS engine (recommended), run the ams executable and specify Engine ReaxFF:

"$AMSBIN"/ams <<EOF
    # ams input
    Engine ReaxFF
       ForceField CHO.ff
    EndEngine
EOF

To run ReaxFF as a standalone program (not recommended unless necessary), run the reaxff executable. The files control, geo, etc., must exist in the current working directory. For more information, see the Old ReaxFF manual.

"$AMSBIN"/reaxff