Table 1. Charmm27 Force Field Parameters Used in Variants of the Alpha-Cristabolite (101̅) Slab.
| Charges | |
|---|---|
| atom | charge (e) |
| bulk silica | +1.10a |
| bulk oxygen | –0.55a |
| silanol oxygen | –0.692b |
| silanol hydrogen | +0.417b |
| van der Waals | ||
|---|---|---|
| atom | ε0 (kcal/mol) | 1/2R0 (Å) |
| bulk silicon | –0.50a | 2.00a |
| bulk oxygen | –0.25a | 1.75a |
| silanol oxygen | –0.1521b | 1.7682b |
| silanol hydrogen | –0.046b | 0.2245b |
| Geometry | ||
|---|---|---|
| spring constant | equilibrium value | |
| O–H | 495 kcal/mol·Å2 a | 0.945 Åa |
| Si–O–H | 50 kcal/mol·rad2 b | 115° a |
a
Parameters accord with those of the SiO2 surface from ref (11), adjusted to the Charmm27 force field.
b
Parameters combined with those of the TIP3P molecule in the Charmm27 force field, ensuring slab neutrality.