Short Range Truncation Schemes
Available truncation schemes for short range interactions
| Keyword | Parameters | Description |
|---|---|---|
None |
– | No truncation scheme |
Cosine |
– | Simple cosine-based truncation, reducing the energy / force to zero over a specified width $\alpha$ leading up to $r_{max}$ $$ r_{trunc} = r - (r_{max} - \alpha $$ $$ E^{cosine}{ij} = \begin{cases} E^{SR}{ij} \left( \frac{1}{2} \left( \cos(\pi \frac{r_{trunc}}{\alpha}) + 1 \right) \right),& r_{trunc} \ge 0 \\ E^{SR}{ij},& \text{otherwise} \end{cases} $$ $$ F^{cosine}{ij} = \begin{cases} \left(F^{SR}{ij} \left( \frac{1}{2} \left( \cos(\pi \frac{r{trunc}}{\alpha}) + 1 \right) \right) \right) \left( -E^{SR}{ij} \pi \sin(\frac{\pi r{trunc}}{\alpha})\frac{1}{\alpha} \right),& r_{trunc} \ge 0 \\ F^{SR}_{ij},& \text{otherwise} \end{cases} $$ |
Shifted |
– | The short-range interaction is shifted such that, at $r = r_{max}$, the contribution to the energy and force is zero. Internally, the energy and force of the interaction at the limit $r_{max}$ are pre-calculated $$ E^{shifted}{ij} = E^{SR}{ij} - \left(r - r_{max}\right) F^{r_{max}}{ij} - E^{r{max}}{ij} $$ $$ F^{shifted}{q_iq_j} = F^{SR}{ij} - F^{r{max}}_{ij} $$ |