Zetterling¶

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

Bases: Pair

Zetterling pair potential.

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.

Zetterling computes the oscillating pair force on all particles in the simulation state:

U(r) = A \frac{\exp{(\alpha r)\cos{(2 k_F r)}}}{r^3} + B \left( \frac{\sigma}{r} \right)^n

The potential was introduced in F. H. M. Zetterling, M. Dzugutov, and S. Lidin 2001.

Example:

nl = nlist.Cell()
zetterling = pair.Zetterling(nl, default_r_cut=2.649, mode="shift")
zetterling.params[("A", "A")] = {
    "A": 1.58,
    "alpha": -0.22,
    "kf": 4.12,
    "B": 0.95533,
    "sigma": 1.0,
    "n": 18.0,
}
zetterling.r_cut[("A", "A")] = 2.649

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 Zetterling:

params¶

The Zetterling potential parameters. The dictionary has the following keys:

A (float, required) - Energy scale of the first term $A$ $[\\mathrm{energy}]$
alpha (float, required) - Screening factor $\\alpha$ $[\\mathrm{length}^{-1}]$
kf (float, required) - Wave number to mimic the Friedel oscillations effect $k_F$ $k_F$ $[\\mathrm{length}^{-1}]$ .
B (float, required) - Energy scale of the second term $B$ $B$ $[\\mathrm{energy}]$ .
sigma (float, required) - Repulsive core size $\\sigma$ $[\\mathrm{length}]$
n (float, required) - The power to take \sigma/r in the second term $n$ $[\\mathrm{dimensionless}]$

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