LennardJonesAttractivePotential #

The attractive part of the Lennard-Jones potential.

\[U(r) = \begin{cases} -\epsilon & (r < \sigma_{ij}\sqrt[6]{2})\\ 4\epsilon \left[\left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^6\right] & (\sigma_{ij}\sqrt[6]{2} < r) \end{cases}\]

Example #

There are two different way to define the parameters. You can either use the normal combining rule or define all the pair-paremeters.

[[forcefields.global]]
interaction = "Pair"
potential   = "LennardJonesAttractive"
ignore.molecule = "Nothing"
ignore.particles_within.bond    = 3
ignore.particles_within.contact = 1
spatial_partition = {type = "CellList", margin = 0.2}

cutoff = 2.5
parameters = [
    {index = 0, offset = 100, sigma = 2.0, epsilon = 10.0},
    # ...
]

To provide pair-parameters manually, define table and give names to the particles.

[[forcefields.global]]
interaction = "Pair"
potential   = "LennardJonesAttractive"
ignore.molecule = "Nothing"
ignore.particles_within.bond    = 3
ignore.particles_within.contact = 1
spatial_partition = {type = "CellList", margin = 0.2}
cutoff = 2.5

table.A.A = {sigma = 1.0, epsilon = 2.0}
table.A.B = {sigma = 3.0, epsilon = 1.0} # B.A will be the same
table.B.B = {sigma = 1.0, epsilon = 1.5}
parameters = [
    {index = 0, offset = 100, name = "A"},
    {index = 1, offset = 100, name = "B"},
    # ...
]

Input Reference #

cutoff: Floating (Optional. By default, 2.5.)
- The cutoff distance relative to the maximum \(\sigma_{ij}\) .
index: Integer
- The index of the particle.
offset: Integer (ptional. By default, 0.)
- Offset value of the index.
sigma: Floating
- It determines the effective particle size. If no table is given, this is required.
epsilon: Integer
- It determines the strength of the potential. If no table is given, this is required.
name: String
- Name of the particle. If table is given, this is required.

For other values, see Pair.