define particle data structure

[dtabell]

The obvious start is

mutable struct Particle
    string name
    PScoord orbit
    Quaternion spin
end

with

mutable struct PScoord
    x
    px
    y
    py
    z
    pz
end

and

mutable struct Quaternion
    w
    x
    y
    z
end

What's missing (besides comments)?

[DavidSagan]

Comments:

• For particle name I think better would be AbstractSpecies from AtomicAndPhysicalConstants.jl
• Since operations on phase space coordinates use a vector, my druthers would be to make orbit a vector.
• To promote interoperability, the spin quaternion should use the struct defined by ReferenceFrameRotations.jl.