| 220 |
|
limited to perfect crystals, but can also apply in disordered fluids. |
| 221 |
|
Even at elevated temperatures, there is local charge balance in an |
| 222 |
|
ionic liquid, where each positive ion has surroundings dominated by |
| 223 |
< |
negaitve ions and vice versa. The reversed-charge images on the |
| 223 |
> |
negative ions and vice versa. The reversed-charge images on the |
| 224 |
|
cutoff sphere that are integral to the Wolf and DSF approaches retain |
| 225 |
|
the effective multipolar interactions as the charges traverse the |
| 226 |
|
cutoff boundary. |
| 524 |
|
used the multipolar Ewald sum as a reference method for comparing |
| 525 |
|
energies, forces, and torques for molecular models that mimic |
| 526 |
|
disordered and ordered condensed-phase systems. The parameters used |
| 527 |
< |
in the test cases are given in table~\ref{tab:pars}. |
| 527 |
> |
in the test cases are given in table~\ref{tab:pars}. |
| 528 |
|
|
| 529 |
|
\begin{table} |
| 530 |
|
\label{tab:pars} |
| 594 |
|
with a reciprocal space cutoff, $k_\mathrm{max} = 7$. Our version of |
| 595 |
|
the Ewald sum is a re-implementation of the algorithm originally |
| 596 |
|
proposed by Smith that does not use the particle mesh or smoothing |
| 597 |
< |
approximations.\cite{Smith82,Smith98} In all cases, the quantities |
| 598 |
< |
being compared are the electrostatic contributions to energies, force, |
| 599 |
< |
and torques. All other contributions to these quantities (i.e. from |
| 600 |
< |
Lennard-Jones interactions) are removed prior to the comparisons. |
| 597 |
> |
approximations.\cite{Smith82,Smith98} This implementation was tested |
| 598 |
> |
extensively against the analytic energy constants for the multipolar |
| 599 |
> |
lattices that are discussed in reference \onlinecite{PaperI}. In all |
| 600 |
> |
cases discussed below, the quantities being compared are the |
| 601 |
> |
electrostatic contributions to energies, force, and torques. All |
| 602 |
> |
other contributions to these quantities (i.e. from Lennard-Jones |
| 603 |
> |
interactions) are removed prior to the comparisons. |
| 604 |
|
|
| 605 |
|
The convergence parameter ($\alpha$) also plays a role in the balance |
| 606 |
|
of the real-space and reciprocal-space portions of the Ewald |
