ExpandedMie¶

class hoomd.md.pair.ExpandedMie(nlist, default_r_cut=None, default_r_on=0.0, mode='none')¶

Bases: Pair

Expanded Mie pair force.

Parameters:

nlist (hoomd.md.nlist.NeighborList) – Neighbor list.
default_r_cut (float) – Default cutoff radius \([\mathrm{length}]\).
default_r_on (float) – Default turn-on radius \([\mathrm{length}]\).
mode (str) – Energy shifting/smoothing mode.

ExpandedMie computes the radially shifted Mie pair force on every particle in the simulation state:

\[U(r) = \left( \frac{n}{n-m} \right) {\left( \frac{n}{m} \right)}^{\frac{m}{n-m}} \varepsilon \left[ \left( \frac{\sigma}{r-\Delta} \right)^{n} - \left( \frac {\sigma}{r-\Delta} \right)^{m} \right]\]

Example:

nl = nlist.Cell()
expanded_mie = pair.ExpandedMie(nlist=nl, default_r_cut=3.0)
mie.params[("A", "B")] = {
    "epsilon": 1.0,
    "sigma": 1.0,
    "n": 12,
    "m": 6,
    "delta": 0.5,
}
expanded_mie.r_cut[("A", "B")] = 2 ** (1.0 / 6.0)
expanded_mie.params[(["A", "B"], ["C", "D"])] = {
    "epsilon": 1.5,
    "sigma": 2.0,
    "n": 12,
    "m": 6,
    "delta": 0.5,
}

Members inherited from AutotunedObject:

property kernel_parameters¶: Kernel parameters. Read more...

property is_tuning_complete¶: Check if kernel parameter tuning is complete. Read more...

tune_kernel_parameters()¶: Start tuning kernel parameters. Read more...

Members inherited from Force:

additional_energy¶: Additional energy term. Read more...

additional_virial¶: Additional virial tensor term \(W_\mathrm{additional}\). Read more...

cpu_local_force_arrays¶: Local force arrays on the CPU. Read more...

energies¶: Energy contribution \(U_i\) from each particle. Read more...

energy¶: The potential energy \(U\) of the system from this force. Read more...

forces¶: The force \(\vec{F}_i\) applied to each particle. Read more...

gpu_local_force_arrays¶: Local force arrays on the GPU. Read more...

torques¶: The torque \(\vec{\tau}_i\) applied to each particle. Read more...

virials¶: Virial tensor contribution \(W_i\) from each particle. Read more...

Members inherited from Pair:

nlist¶: Neighbor list used to compute the pair force. Read more...

mode¶: Energy smoothing/cutoff mode. Read more...

r_cut¶: Cuttoff radius beyond which the energy and force are 0. Read more...

r_on¶: Radius at which the XPLOR smoothing function starts. Read more...

compute_energy()¶: Compute the energy between two sets of particles. Read more...

Members defined in ExpandedMie:

params¶

The Expanded Mie potential parameters. The dictionary has the following keys:

epsilon (float, required) - \(\epsilon\) \([\mathrm{energy}]\).
sigma (float, required) - \(\sigma\) \([\mathrm{length}]\).
n (float, required) - \(n\) \([\mathrm{dimensionless}]\).
m (float, required) - \(m\) \([\mathrm{dimensionless}]\).
delta (float, required) - \(\Delta\) \([\mathrm{length}]\).

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