Simulations of energetic beam deposition: from picoseconds to seconds

We present a new method for simulating crystal growth by energetic beam deposition. The method combines a Kinetic Monte-Carlo simulation for the thermal surface diffusion with a small scale molecular dynamics simulation of every single deposition event. We have implemented the method using the effective medium theory as a model potential for the atomic interactions, and present simulations for Ag/Ag(111) and Pt/Pt(111) for incoming energies up to 35 eV. The method is capable of following the growth of several monolayers at realistic growth rates of 1 monolayer per second, correctly accounting for both energy-induced atomic mobility and thermal surface diffusion. We find that the energy influences island and step densities and can induce layer-by-layer growth. We find an optimal energy for layer-by-layer growth (25 eV for Ag), which correlates with where the net impact-induced downward interlayer transport is at a maximum. A high step density is needed for energy induced layer-by-layer growth, hence the effect dies away at increased temperatures, where thermal surface diffusion reduces the step density. As part of the development of the method, we present molecular dynamics simulations of single atom-surface collisions on flat parts of the surface and near straight steps, we identify microscopic mechanisms by which the energy influences the growth, and we discuss the nature of the energy-induced atomic mobility

Tactical Agriculture (TAg) In New York State: On-Farm IPM Education in Field Corn, Alfalfa, Soybeans and Vegetables

The Tactical Agriculture (TAg) program is an experiential, hands-on training program designed to teach integrated pest and crop management concepts to field crop producers and other agribusiness personnel. The TAg program, which has been active in New York State since 1990, teaches field crop producers to better manage field crops, protect the environment and reduce health risks associated with production agriculture. Participants are actively engaged in a growing-season-long educational program that discusses critical pest and crop management issues that arise during the growing season and reinforces the learning experience with the timely collection of data from their fields during the growing season. In 2006, 81 producers in 10 counties in New York State participated in TAg teams covering Integrated Pest Management and Integrated Crop Management topics in field corn, alfalfa and other hay crops, soybeans, and vegetables