"A fast multipole method combined with a reaction field for long-range electrostatics in molecular dynamics simulations: The effects of truncation on the properties of water
"G. Mathias, B. Egwolf, M. Nonella, and P. Tavan
J. Chem. Phys. 118, 10847-10860 (2003)
We present a combination of the structure adapted multipole method (SAMM)
with a reaction field (RF)
correction for the efficient evaluation of electrostatic interactions
in molecular dynamics simulations under periodic boundary conditions.
The algorithm switches from an explicit electrostatics evaluation
to a continuum description at the maximal distance that is consistent
with the minimum image convention, and, thus, avoids the use of a
periodic electrostatic potential.
A physically motivated switching function
enables charge clusters interacting with a given charge to smoothly move
into the solvent continuum by passing
through the spherical dielectric boundary
surrounding this charge.
This transition is complete as soon as the cluster has reached the so-called truncation radius Rc.
The algorithm is used to examine the dependence of thermodynamic properties and
correlation functions on Rc in the three point transferable intermolecular potential (TIP3P)
Our test simulations on pure liquid water
used either the RF correction or a straight cutoff and
values of Rc ranging from 14 Å to 40 Å.
In the RF setting, the thermodynamic properties and the correlation functions
show convergence for increasing Rc towards 40 Å.
In the straight cutoff case no such convergence is found.
Here, in particular, the dipole-dipole
correlation functions become completely artificial.
The RF description of the long-range electrostatics is verified by
comparison with the results of a particle-mesh Ewald simulation at
BMO authors (in alphabetic order):
Long-range electrostatics in molecular dynamics simulations