Development of a Charge-Implicit ReaxFF for C/H/O Systems

Modeling chemical
reactions in condensed phases is difficult. Interaction
potentials (or force fields) like ReaxFF can perform this modeling
with a high overall accuracy, but the disadvantage of ReaxFF is a
low simulation speed arising from costly algorithms, in particular
charge equilibration. Therefore, we reparametrized ReaxFF to incorporate
Coulomb forces into other terms of the force field. Because of this
change, our charge-implicit ReaxFF-CHO is >2 times faster than
the
original parametrization. Despite the lack of explicit electrostatic
interactions, our potential can correctly model the reactions and
densities of systems containing carbon, hydrogen, and oxygen atoms.
We have used the new potential to simulate bombardment of trehalose
by water clusters. It has been observed experimentally that these
water projectiles can increase the sensitivity of secondary ion mass
spectrometry by more than an order of magnitude, but no explanation
for this phenomenon was given. Our simulations show that the increase
in the intensity of the recorded signal coincides with the emission
of trehalose–water complexes.