diff --git a/src/atomsbase.jl b/src/atomsbase.jl
index aea44b2..dc77922 100644
--- a/src/atomsbase.jl
+++ b/src/atomsbase.jl
@@ -14,31 +14,35 @@ export get_cell, AosSystem, SoaSystem, ChemicalElement
 # an `Atom` is now just a `PState`, so we define 
 # accessors for the PState fields with canonical names. 
 
-symbol(::typeof(position)) = :𝐫 
-symbol(::typeof(velocity)) = :𝐯
-symbol(::typeof(atomic_mass)) = :𝑚
-symbol(::typeof(atomic_symbol)) = :𝑍
-
-const _atom_syms = (𝐫 = position, 
-                    𝐯 = velocity, 
-                    𝑚 = atomic_mass, 
-                    𝑍 = atomic_symbol)
-
-position(atom::PState) = atom.𝐫 
-velocity(atom::PState) = atom.𝐯
-atomic_mass(atom::PState) = atom.𝑚
-atomic_symbol(atom::PState) = atom.𝑍   # this one I'm not sure about 
+# list of properties that DP knows about: 
+_list_of_properties = [ 
+   (:𝐫, :position),
+   (:𝐯, :velocity),
+   (:𝑚, :atomic_mass),
+   (:𝑍, :atomic_symbol),
+   (:𝑞, :charge),
+   (:μ, :dipole), 
+   (:𝐩, :momentum),
+   (:𝐸, :energy),
+   (:𝑀, :mass),
+   ]
+
+for (sym, name) in _list_of_properties
+   @eval $name(x::XState) = x.$sym
+   @eval symbol(::typeof($name)) = $(Meta.quot(sym))
+end
 
 atomic_number(atom::PState) = atomic_number(atomic_symbol(atom))
 
-_post(a) = a 
-_post(sym::Symbol) = ChemicalElement(sym)
+_post(p, a) = a 
+_post(::typeof(atomic_symbol), sym::Symbol) = ChemicalElement(sym)
+_post(::typeof(atomic_symbol), z::Integer) = ChemicalElement(z)
 
 """ 
 Generate an atom with the given properties. 
 """
 atom(at; properties = (position, atomic_mass, atomic_symbol)) = 
-      PState((; [symbol(p) => _post(p(at)) for p in properties]...))
+      PState((; [symbol(p) => _post(p, p(at)) for p in properties]...))
 
 # --------------------------------------------------- 
 # Array of Structs System 
@@ -68,10 +72,10 @@ Base.length(at::AosSystem) = length(at.particles)
 Base.getindex(at::AosSystem, i::Int) = at.particles[i]
 Base.getindex(at::AosSystem, inds::AbstractVector) = at.particles[inds]
 
-for f in (:position, :velocity, :atomic_mass, :atomic_symbol)
-   @eval $f(sys::AosSystem) = [ $f(x) for x in sys.particles ]
-   @eval $f(sys::AosSystem, i::Integer) = $f(sys.particles[i]) 
-   @eval $f(sys::AosSystem, inds::AbstractVector) = [$f(sys.particles[i]) for i in inds]
+for (sym, name) in [ _list_of_properties; [(:ignore, :atomic_number) ] ]
+   @eval $name(sys::AosSystem) = [ $name(x) for x in sys.particles ]
+   @eval $name(sys::AosSystem, i::Integer) = $name(sys.particles[i])
+   @eval $name(sys::AosSystem, inds::AbstractVector) = [$name(sys.particles[i]) for i in inds]
 end
 
 # AtomsBase. 
@@ -95,7 +99,7 @@ end
 function SoaSystem(sys::AbstractSystem; 
                    properties = (position, atomic_mass, atomic_symbol), )
 
-   arrays = (; [symbol(p) => _post.(p(sys)) for p in properties]... )
+   arrays = (; [symbol(p) => _post.(p, p(sys)) for p in properties]... )
    cell = get_cell(sys)
    D = AtomsBase.n_dimensions(cell)
    return SoaSystem{D, typeof(cell), typeof(arrays)}(
@@ -130,13 +134,14 @@ end
 Base.getindex(sys::SoaSystem, inds::AbstractVector{<: Integer}) = 
       [ sys[i] for i in inds ]
 
-for f in (:position, :velocity, :atomic_mass, :atomic_symbol)
-   @eval $f(sys::SoaSystem) = getfield(sys.arrays, symbol($f))
-   @eval $f(sys::SoaSystem, i::Integer) = getfield(sys.arrays, symbol($f))[i]
-   @eval $f(sys::SoaSystem, inds::AbstractVector) = getfield(sys.arrays, symbol($f))[inds]
+
+for (sym, name) in [ _list_of_properties; [(:ignore, :atomic_number) ] ]
+   @eval $name(sys::SoaSystem) = copy(sys.arrays.$sym)
+   @eval $name(sys::SoaSystem, i::Integer) = sys.arrays.$sym[i]
+   @eval $name(sys::SoaSystem, inds::AbstractVector) = sys.arrays.$sym[inds]
 end
 
-# AtomsBase.
+
 get_cell(at::SoaSystem) = at.cell
 
 for f in (:n_dimensions, :bounding_box, :boundary_conditions, :periodicity)
@@ -149,37 +154,49 @@ end
 # ---------------------------------------------------------------
 #  Extension of the AtomsBase interface with setter functions 
 
-export set_position, 
-       set_position!, 
-       set_positions!, 
-       set_bounding_box!
-
-set_position(x::PState, 𝐫::SVector) = setproperty(x, :𝐫, 𝐫)
-
-function set_position!(sys::AosSystem, i::Integer, 𝐫::SVector)
-   xi = sys.particles[i]
-   sys.particles[i] = set_position(xi, 𝐫)
-   return nothing 
-end
-
-function set_positions!(sys::AosSystem, R::AbstractVector{<: SVector})
-   for i = 1:length(sys) 
-      set_position!(sys, i, R[i])
+for (sym, name) in _list_of_properties
+   set_name = Symbol("set_$name")
+   set_name_ip = Symbol("set_$(name)!")
+   set_names_ip = Symbol("set_$(name)s!")
+   @eval export $set_name, $set_name_ip, $set_names_ip 
+   # e.g. set_position(x::PState, 𝐫) = setproperty(x, :𝐫, 𝐫)
+   @eval $set_name(x::PState, t) = setproperty(x, $(Meta.quot(sym)), t)
+   # e.g. set_position!(sys, i, 𝐫)
+   @eval begin
+      function $set_name_ip(sys::AosSystem, i::Integer, t) 
+         xi = sys.particles[i] 
+         sys.particles[i] = $set_name(xi, t)
+         return nothing 
+      end
+   end
+   @eval begin 
+      function $set_name_ip(sys::SoaSystem, i::Integer, t)
+         sys.arrays.$sym[i] = t
+         return nothing 
+      end
+   end
+   # e.g. set_positions!(sys, X)
+   @eval begin
+      function $set_names_ip(sys::AosSystem, Rs) 
+         for i = 1:length(sys) 
+            $set_name_ip(sys, i, Rs[i])
+         end
+      end
+      return nothing 
+   end
+   @eval begin 
+      function $set_names_ip(sys::SoaSystem, R::AbstractVector)
+         copy!(sys.arrays.$sym, R)
+         return nothing 
+      end
    end
-   return nothing 
 end
 
+# todo: set_atomic_number & co 
 
-function set_position!(sys::SoaSystem, i::Integer, 𝐫::SVector)
-   sys.arrays.𝐫[i] = 𝐫
-   return nothing 
-end
-
-function set_positions!(sys::SoaSystem, R::AbstractVector{<: SVector})
-   copy!(sys.arrays.𝐫, R)
-   return nothing 
-end
+# cell-level setter 
 
+export set_bounding_box!
 
 function set_bounding_box!(sys::Union{SoaSystem, AosSystem}, bb)
    cell = PCell(bb, periodicity(sys))
diff --git a/src/states.jl b/src/states.jl
index 37d1e10..52e46fe 100644
--- a/src/states.jl
+++ b/src/states.jl
@@ -9,7 +9,7 @@ import Base: *, +, -, zero, rand, randn, show, promote_rule, rtoldefault,
 
 import LinearAlgebra: norm, promote_leaf_eltypes
 
-export PState, VState, vstate_type 
+export PState, VState, vstate_type, setproperty 
 
 abstract type XState{NT <: NamedTuple} end 
 
diff --git a/test/test_atomsbase.jl b/test/test_atomsbase.jl
index d17df6e..419a4d6 100644
--- a/test/test_atomsbase.jl
+++ b/test/test_atomsbase.jl
@@ -18,6 +18,7 @@ display(x)
 @test atomic_symbol(x) == x.𝑍
 @test atomic_number(x) == 6
 
+
 ## 
 #convert an Atom 
 
@@ -27,7 +28,9 @@ display(x)
 @test x.𝐫 == position(x) == position(at)
 @test x.𝑚 == atomic_mass(x) == atomic_mass(at)
 @test x.𝑍 == atomic_symbol(x) == atomic_symbol(at)
-
+@test DP.symbol(position) == :𝐫
+@test DP.symbol(atomic_mass) == :𝑚
+@test DP.symbol(atomic_symbol) == :𝑍
 
 ## 
 # convert an entire system