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Mesocrystal particle

A mesocrystal combines a three-dimensional crystal with a finite outer shape. The crystal defines the lattice and its basis particle; the outer shape selects the lattice sites that belong to the mesocrystal.

# Particle at each lattice site
inner_shape = ba.Sphere(3*nm)
basis = ba.Particle(material, inner_shape)

# Three-dimensional lattice
lattice = ba.Lattice3D(
    ba.R3(8*nm, 0, 0),
    ba.R3(0, 8*nm, 0),
    ba.R3(0, 0, 8*nm),
)

# Lattice and basis
crystal = ba.Crystal(basis, lattice)

# Finite mesocrystal
outer_shape = ba.Cylinder(20*nm, 50*nm)
mesocrystal = ba.Mesocrystal(crystal, outer_shape)

The basis can be a simple Particle or a particle composition such as a Compound, CoreAndShell, or another Mesocrystal. The Mesocrystal with basis example uses a Compound as the basis.

The outer shape must be a closed hard form factor. It selects complete lattice sites and does not clip basis particles at the surface.

By default, BornAgain sums the selected lattice sites exactly. An approximate reciprocal-space algorithm is available for large mesocrystals; see Mesocrystal summation.

Examples

  • Mesocrystal compares exact and reciprocal-space summation.