Linear

class hoomd.hpmc.external.Linear(default_alpha=None, plane_origin=(0, 0, 0), plane_normal=(0, 1, 0))

Bases: External

Linear external potential (HPMC).

Parameters:

• default_alpha (float) – Default value for alpha $[\mathrm{energy}] [\mathrm{length}]^{-1}$

• plane_origin ([float, float, float]) – A point on the plane of 0 energy.

• plane_normal ([float, float, float]) – A vector perpendicular to the plane of 0 energy.

Linear computes a linear external potential on all particles in the simulation state:

$$U_{\mathrm{external},i} = \alpha_i \cdot \vec{n} \cdot ( \vec{r}_i - \vec{p} )$$

where $\alpha_i$ (alpha) is the linear energy coefficient , $\vec{n}$ is the normal vector to the plane (plane_normal), and $\vec{p}$ is the plane origin (plane_origin):

Example

linear = hoomd.hpmc.external.Linear()
linear.alpha["A"] = 0.2
simulation.operations.integrator.external_potentials = [linear]

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Members inherited from External:

property energy

Potential energy contributed by this potential $[\mathrm{energy}]$. Read more...

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Members defined in Linear:

alpha

The linear energy coefficient $\alpha$ by particle type.

Type: TypeParameter [tuple [particle_type, particle_type], float]

plane_origin

A point on the plane where the energy is zero.

Type: (float, float, float)

plane_normal

A unit length vector perpendicular to the plane where the energy is zero.

Type: (float, float, float)