# ReaxFF

Complex processes such as combustion, CVD, battery discharge
Studied atomistically with reactive MD, great GUI and tools

# ReaxFF

## Reactive MD with GUI and analysis tools

ReaxFF is a program for modeling chemical reactions with atomistic potentials based on the reactive force field approach. In collaboration with the van Duin group, SCM has parallelized and significantly optimized the original ReaxFF code. Reactions in complex chemical mixtures totaling hundreds of thousands of atoms can now be modeled on a modern desktop computer.

While traditional force fields have difficulties treating certain elements, such as transition metals, the bond-order based reactive force field can in principle deal with the whole periodic table. We include over 50 parameter files for many different combinations of elements. Furthermore, a (re)parameterization tool helps to refine force fields or build new parameter sets. ReaxFF has been used over the past decade in various studies of complicated reactive systems, including solvent environments, interfaces, and molecules on metal (oxide) surfaces.

## GUI: preparation, execution & analysis

• easy to set up complex systems with Packmol builder
• define temperature, volume, and electric field regimes
• various thermostats and barostats
• pressure and bond constraints
• local and remote execution, job monitoring
• analyze changing molecular composition and reaction pathways (ChemTraYzer)
• molecule gun

## ReaxFF features

• geometry optimization, non-reactive or reactive molecular dynamics
• various ReaxFF force fields
• MCFF Optimizer: force field parameterization tool
• model reactions of millions of atoms in a 3D box
• well parallelized and linear-scaling for large systems
• Grand-Canonical Monte Carlo: reactivity under thermodynamic equilibrium conditions
• force-bias Monte Carlo: accelerated reactive MD
• ACKS2 charge equilibration: correct long-range charge behavior (batteries, enzymes)
• eReaxFF: explicit electrons

The ReaxFF reactive force field: development, applications and future directions” is an excellent introduction to the current state of reactive molecular dynamics.

## Hands-on two-day workshop

A two-day hands-on workshop was organized on September 27 and 28 2016 by NSCCS at Imperial College London, with tutors from SCM and invited experts Adri van Duin, Susanna Monti & Eldhose Iype. The topics covered were accelerated dynamics with force bias Monte Carlo (fbMC), grand canonical Monte Carlo (GCMC) and parameterization with MCFF. The program, description and materials of the ReaxFF workshop are available from the workshop page.

If you use your own force field, either from literature or by modifying an existing force field, it is advisable to clean up your force field withthis script
\$ADFBINstartpython cleanreaxffforcefield.py -i [input ffield] -o [output ffield]