We present a general numerical framework for modeling plasma processin
g devices, Based on the particle-in-cell method, in which any material
can be represented by particles, we model plasmas, fluids, dust parti
cles and structures, and their interactions, We define classes of part
icles, each of which represents a different material, and each of whic
h is hosted by an independent code module, For example, an object modu
le represents structures and imposes boundary conditions corresponding
to complex geometries on to the plasma and fluid particles, We descri
be the formulation of PIC for a drift-diffusion model, calculate the i
nteraction with dielectrics and conductors, compare the results of the
code with calculations of DC discharges, and present an example that
illustrates the geometric complexity that can be modeled.