background: the monte carlo method is the most accurate method for simulation of radiation therapy equipment. the linear accelerators are currently the most widely used machines in radiation therapy centers. methods: in this work, a monte carlo modelling of the siemens oncor linear accelerator in 6 mv and 18 mv beams was performed. the results of simulation were validated by measurements in wat...

A hybrid multiscale kinetic Monte Carlo (HMKMC) method for speeding up the simulation of copper electrodeposition is presented. The fast diffusion events are simulated deterministically with a heterogeneous diffusion model which considers site-blocking effects of additives. Chemical reactions are simulated by an accelerated (tau-leaping) method for discrete stochastic simulation which adaptivel...

The dynamics near firstand second-order phase transitions in a two-dimensional lattice-gas model are compared using the first-order reversal curve (FORC) method. The FORC diagram of a first-order transition is characterized by a negative region separating two positive regions, reflecting a competition between the time-varying electrochemical potential and the tendency of the system to phase order.

The effects of adsorbates on nucleation and growth of twodimensional islands is investigated by kinetic Monte Carlo simulations and rate equation theory. The variation of island morphology with adsorbate parameters is discussed and the temperature-dependence of island density in the case of immobile adsorbates is studied in detail. A set of rate equations for the description of nucleation in th...

We show that fast edge diffusion in a simple kinetic Monte Carlo simulation for epitaxial growth enhances surface roughening for a model of irreversible aggregation. The reason for this is a simple, but rather subtle effect: Faster edge diffusion makes the islands more compact, leading to a significant adatom concentration on top of islands at earlier times. As a consequence, nucleation in high...

Thin-film deposition is an industrially important process that is highly dependent on the processing conditions. Most films are grown under constant conditions, but a few studies show that modified properties may be obtained with periodic inputs. However, assessing the effects of modulation experimentally becomes impractical with increasing material complexity. Here we consider periodic conditi...

RICHARD WEINKAMER*, PETER FRATZL, HIMADRI S. GUPTA, OLIVER PENROSE and JOEL L. LEBOWITZ Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany; Department of Mathematics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, Scotland, UK; Departments of Mathematics and Physics, Rutgers University, Hill Center, Busch Campus, New Brunswick, 08903 New ...

The effects of oblique incidence on the surface roughness in low-temperature Cu /Cu 100 epitaxial growth are investigated via kinetic Monte Carlo simulations, which include the effects of shadowing as well as short-range and long-range attraction. While the effects of deposition angle are found to be relatively weak at 200 K, at a slightly lower temperature 160 K both the surface roughness and ...

Recently, it has become possible to unfold a single protein molecule titin, by pulling it with an atomic-force-microscope tip. In this paper, we propose and study a stochastic kinetic model of this unfolding process. Our model assumes that each immunoglobulin domain of titin is held together by six hydrogen bonds. The external force pulls on these bonds and lowers the energy barrier that preven...

We propose a stochastic model for molecular transport at the nanoscale that describes the motion of two-dimensional molecular assemblies called multivalent random walkers (MVRWs). This walker model is an abstract description of the motion of multipedal molecular assemblies, called molecular spiders, which use deoxyribozyme legs to move over a surface covered with substrate DNA molecules, cleavi...