type PBEparticle ={
    FractalIndex: Double(unit="U"),
    Bondforce: Double(unit="N"),
    Density: Double(unit="kg/m^3"),
    RefractiveIndex: Double(unit="U"),
    UVabsorption: (Double(unit="1/s"), Double(unit="1/s")),
    SurfacePotential: Double(unit="V"),
    SurfaceCharge: Double,
    RPermittivity: Double(unit="U"),
    AvgRadius: Double(unit="m")
}