BornAgain
≻ git-develop
≻ Documentation ≻ Reference ≻ Sample model ≻ Particles ≻ Composite particles ≻ Mixture
BornAgain
≻ git-develop
≻ Documentation ≻ Reference ≻ Sample model ≻ Particles ≻ Composite particles ≻ Mixture
A Mixture is a probabilistic particle: at each placement, it
resolves to one of its configured particle types — the possible
outcomes — with probabilities given by the (internally normalized)
abundance weights. This is especially suited to uncorrelated
compositional disorder: random substitutions at lattice sites, or
species mixing in dilute distributions.
mix = ba.Mixture()
mix.addParticle(particle_1, 0.8)
mix.addParticle(particle_2, 0.2)
mix.nbrParticles() returns the number of added particle alternatives
(2 here), regardless of their abundance weights.
Equal abundances may also be expressed without normalization:
mix.addParticle(particle_1, 1)
mix.addParticle(particle_2, 1)
A Mixture can be used as the particle in Dilute2D or as the basis
particle of an ordered structure such as
RadialParacrystal.
A Mixture can also appear inside other particles: as a
component of a Compound, as the core of a
CoreAndShell, or as the basis of a
Mesocrystal. The random choice is then made
independently for each instance of the enclosing particle, e.g.
for each lattice site of a mesocrystal. A mesocrystal computed
with the reciprocal-space sum requires a basis without Mixture.
Compared with Compound, which coherently sums the
form factors of its constituents at fixed positions, Mixture
represents the incoherent case: each particle type contributes to
the scattered intensity independently, weighted by its abundance,
with no interference between different types.