A computer-implemented method for simulating a temporal process which locally changes distribution of particle types in a body of a semiconductor during or as results of a fabrication process step, the body of the semiconductor comprising a moving boundary between a first material and a second material, wherein a particle type is a defect, a dopant, an atom of the semiconductor, or a molecule of the semiconductor, the method comprising: in a computer system, imposing a uniform grid of nodes in the body, the grid having three independent dimensions and having a uniform node spacing which is less than the quantum separation distance in silicon, the quantum separation distance in silicon being about 1.1 nanometers; assigning one respective particle of the body to each of a plurality of nodes of the grid; providing a system of first node equations, including at least one node equation for each of the plurality of nodes, the node equation or equations for each particular one of the nodes describing a variation of particle type of the body at the particular node through each of a first plurality of time steps of the temporal process; and the computer system (i) iterating through the first plurality of the time steps to solve the at least one node equation for each of the plurality of nodes and determine a distribution of the particle types of the body according to the moving boundary, at the end of the first plurality of time steps; (ii) using the determined particle types of the body to modify the boundary between the first material and the second material, by re-assigning the respective particle types to the respective particles of the body assigned to the plurality of nodes of the grid and (iii) using the distribution of the particle types of the body of the semiconductor to develop or improve a fabrication process flow. in a computer system, imposing a uniform grid of nodes in the body, the grid having three independent dimensions and having a uniform node spacing which is less than the quantum separation distance in silicon, the quantum separation distance in silicon being about 1.1 nanometers; assigning one respective particle of the body to each of a plurality of nodes of the grid; providing a system of first node equations, including at least one node equation for each of the plurality of nodes, the node equation or equations for each particular one of the nodes describing a variation of particle type of the body at the particular node through each of a first plurality of time steps of the temporal process; and the computer system (i) iterating through the first plurality of the time steps to solve the at least one node equation for each of the plurality of nodes and determine a distribution of the particle types of the body according to the moving boundary, at the end of the first plurality of time steps; (ii) using the determined particle types of the body to modify the boundary between the first material and the second material, by re-assigning the respective particle types to the respective particles of the body assigned to the plurality of nodes of the grid and (iii) using the distribution of the particle types of the body of the semiconductor to develop or improve a fabrication process flow.