TABLE I.
Percentage error for Coulomb energies between water molecules calculated and RMS Coulomb gradient given by LREC with respect to PME and the computation time (Intel Core-i7-920 processor @ 2.66G with 12 GB memory) for both methods at different cutoffs for the interactions are shown in Table I.
| Cutoffs (Å) | Percentage error for Coulomb energy (LREC vs PME) | Percentage error for final RMS Coulomb gradient (LREC vs PME) | Computing time for LREC (s) | Computing time for PME (s) |
|---|---|---|---|---|
| 8 | 1.07 | 1.07 | 4.632 | 5.435 |
| 9 | −0.87 | 1.05 | 5.028 | 5.768 |
| 10 | 1.55 | 0.68 | 5.244 | 5.035 |
| 11 | −0.03 | 0.57 | 5.443 | 5.04 |
| 12 | 0.41 | 0.51 | 5.645 | 5.038 |
| 13 | 0.78 | 0.4 | 5.44 | 5.039 |
| 14 | 0.72 | 0.35 | 5.645 | 5.041 |
| 15 | 0.41 | 0.34 | 5.439 | 5.037 |
| 16 | 0.53 | 0.29 | 5.446 | 5.24 |
| 17 | 0.27 | 0.25 | 5.641 | 5.035 |
| 18 | 0.65 | 0.23 | 5.639 | 5.037 |
| 19 | −0.44 | 0.2 | 5.638 | 5.241 |
| 20 | 0.2 | 0.18 | 5.844 | 5.433 |
| 21 | 0.24 | 0.16 | 6.04 | 5.434 |
| 22 | −0.03 | 0.15 | 6.239 | 5.437 |
| 23 | 0.3 | 0.14 | 6.246 | 5.639 |
| 24 | 0.27 | 0.12 | 6.442 | 5.637 |
| 25 | 0.14 | 0.12 | 6.639 | 5.836 |
| 26 | 0.74 | 0.01 | 6.839 | 6.037 |
| 27 | 0.2 | 0.01 | 7.043 | 6.238 |
| 28 | 0.36 | 0.01 | 7.24 | 6.435 |
| 29 | 0.4 | 0.03 | 7.643 | 6.432 |
| 30 | 0.56 | 0.03 | 7.844 | 6.84 |