Table 1.
Analytic and numerical forces (kcal mol−1 Å−1) calculated by the X-Pol-Ewald method for two water molecules (water number 34 and 35) in a cubic box consisting of 216 water molecules. Numerical forces are determined by finite difference from displacements of atomic positions and differences specify the deviation of analytic forces from the numerical ones
| Atom number | dimension | analytic | numerical | difference |
|---|---|---|---|---|
| 100 | X (O34) | −0.96117 | −0.96109 | 0.00008 |
| 100 | Y (O34) | −2.14231 | −2.14238 | −0.00006 |
| 100 | Z (O34) | 0.40245 | 0.40233 | −0.00012 |
| 101 | X (H34) | 1.41450 | 1.41454 | 0.00004 |
| 101 | Y (H34) | −1.15551 | −1.15545 | 0.00006 |
| 101 | Z (H34) | −1.24614 | −1.24613 | 0.00001 |
| 102 | X (H34) | 1.07218 | 1.07211 | −0.00008 |
| 102 | Y (H34) | −1.27491 | −1.27476 | 0.00016 |
| 102 | Z (H34) | −1.01582 | −1.01575 | 0.00006 |
| 103 | X (O35) | 4.73798 | 4.73802 | 0.00004 |
| 103 | Y (O35) | 0.96007 | 0.96017 | 0.00010 |
| 103 | Z (O35) | −3.78347 | −3.78341 | 0.00007 |
| 104 | X (H35) | 0.78805 | 0.78800 | −0.00005 |
| 104 | Y (H35) | −1.64549 | −1.64555 | −0.00007 |
| 104 | Z (H35) | −1.01468 | −1.01458 | 0.00010 |
| 105 | X (H35) | −0.24715 | −0.24712 | 0.00003 |
| 105 | Y (H35) | −1.55094 | −1.55094 | 0.00000 |
| 105 | Z (H35) | −0.17444 | −0.17460 | −0.00017 |