Moliere¶

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

Bases: Pair

Moliere 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.

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

U(r) = \frac{Z_i Z_j e^2}{4 \pi \epsilon_0 r_{ij}} \left[ 0.35 \exp \left( -0.3 \frac{r_{ij}}{a_F} \right) + \\ 0.55 \exp \left( -1.2 \frac{r_{ij}}{a_F} \right) + 0.10 \exp \left( -6.0 \frac{r_{ij}}{a_F} \right) \right]

Where each parameter is defined as:

$Z_i$ - Z_i - Atomic number of species i $[\mathrm{dimensionless}]$
$Z_j$ - Z_j - Atomic number of species j $[\mathrm{dimensionless}]$
$e$ - elementary_charge - The elementary charge $[\mathrm{charge}]$
$a_F = \frac{0.8853 a_0}{\left( \sqrt{Z_i} + \sqrt{Z_j} \right)^{2/3}}$ , where $a_0$ is the Bohr radius $[\mathrm{length}]$

Example:

nl = nlist.Cell()
moliere = pair.Moliere(default_r_cut = 3.0, nlist=nl)

Zi = 54
Zj = 7
e = 1
a0 = 1
aF = 0.8853 * a0 / (np.sqrt(Zi) + np.sqrt(Zj))**(2/3)

moliere.params[('A', 'B')] = dict(qi=Zi*e, qj=Zj*e, aF=aF)

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 Moliere:

params¶

The potential parameters. The dictionary has the following keys:

qi (float, required) - $q_i = Z_i \frac{e}{\sqrt{4 \pi \epsilon_0}}$ $[\mathrm{charge}]$
qj (float, required) - $q_j = Z_j \frac{e}{\sqrt{4 \pi \epsilon_0}}$ $[\mathrm{charge}]$
aF (float, required) - $a_F = \frac{0.8853 a_0}{\left( \sqrt{Z_i} + \sqrt{Z_j} \right)^{2/3}}$ $[\mathrm{length}]$

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