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Particle 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)

Equal abundances may also be expressed without normalization:

mix.addParticle(particle_1, 1)
mix.addParticle(particle_2, 1)

Like every IParticle, a Mixture can be deposited directly in a Layer, wrapped in Dilute2D, or used as the basis particle of an ordered structure such as RadialParacrystal.

Physics

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.

Examples