Development of a Transferable Reactive Force Field of P/H Systems: Application to the Chemical and Mechanical Properties of Phosphorene

We developed ReaxFF
parameters for phosphorus and hydrogen to give
a good description of the chemical and mechanical properties of pristine
and defected black phosphorene. ReaxFF for P/H is transferable to
a wide range of phosphorus- and hydrogen-containing systems including
bulk black phosphorus, blue phosphorene, edge-hydrogenated phosphorene,
phosphorus clusters, and phosphorus hydride molecules. The potential
parameters were obtained by conducting global optimization with respect
to a set of reference data generated by extensive ab initio calculations.
We extended ReaxFF by adding a 60° correction term, which significantly
improved the description of phosphorus clusters. Emphasis was placed
on the mechanical response of black phosphorene with different types
of defects. Compared to the nonreactive SW potential (Jiang, J.-W. Nanotechnology 2015, 26, 315706), ReaxFF for P/H systems provides a significant improvement in describing
the mechanical properties of the pristine and defected black phosphorene,
as well as the thermal stability of phosphorene nanotubes. A counterintuitive
phenomenon is observed that single vacancies weaken the black phosphorene
more than double vacancies with higher formation energy. Our results
also showed that the mechanical response of black phosphorene is more
sensitive to defects in the zigzag direction than that in the armchair
direction. In addition, we developed a preliminary set of ReaxFF parameters
for P/H/O/C to demonstrate that the ReaxFF parameters developed in
this work could be generalized to oxidized phosphorene and P-containing
2D van der Waals heterostructures. That is, the proposed ReaxFF parameters
for P/H systems establish a solid foundation for modeling of a wide
range of P-containing materials.