angle¶
Angle force classes apply a force and virial on every particle in the simulation state commensurate with the potential energy:
\[U_\mathrm{angle} = \sum_{(i,j,k) \in \mathrm{angles}} U_{ijk}(\theta)\]
Each angle is defined by an ordered triplet of particle tags in the
hoomd.State member angle_group. HOOMD-blue does not construct angle
groups, users must explicitly define angles in the initial condition.
In the angle group (i,j,k), \(\theta\) is the angle between the vectors \(\vec{r}_{ij}\) and \(\vec{r}_{kj}\).
Angle force classes assign 1/3 of the potential energy to each of the particles in the angle group:
\[U_l = \frac{1}{3} \sum_{(i,j,k) \in \mathrm{angles}}
U_{ijk}(\theta) [l=i \lor l=j \lor l=k]\]
and similarly for virials.
Classes