Path integral representation of the Dirac equation and integration order

In this paper we ask if there is an interesting twist in mathematics of the Feynman propagator of the present day [1] formalism for the Dirac equation. The case studied is with only a potential function V . If there is no special integration order per step for e.g. dx(0) = dx1dx2dx3 and dp(0) = dp1dp2dp3, then a delta function occurs when c∆t ≈ 0 and −∞ < pj < ∞ for j = 1,2,3. The found geoemtry of propagation can be tested in solid state chemistry. A crystal structure where only a two dimensional propagation of quasi particles can be created must be attached to the final step of the path integral. Neutron emission giving chemical isotopes is briefly discussed.