Morse¶

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

Bases: Pair

Morse 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.

Morse computes the Morse pair force on every particle in the simulation state:

\[U(r) = D_0 \left[ \exp \left(-2\alpha\left( r-r_0\right)\right) -2\exp \left(-\alpha\left(r-r_0\right) \right) \right]\]

Example:

nl = nlist.Cell()
morse = pair.Morse(default_r_cut=3.0, nlist=nl)
morse.params[("A", "A")] = dict(D0=1.0, alpha=3.0, r0=1.0)
morse.r_cut[("A", "B")] = 3.0

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 Morse:

params¶

The potential parameters. The dictionary has the following keys:

D0 (float, required) - depth of the potential at its minimum \(D_0\) \([\mathrm{energy}]\)
alpha (float, required) - the width of the potential well \(\alpha\) \([\mathrm{length}^{-1}]\)
r0 (float, required) - position of the minimum \(r_0\) \([\mathrm{length}]\)

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