Modelling (100) hydrogen-induced platelets in silicon with a multi-scale molecular dynamics approach

We introduce a multiscale molecular dynamics (MD) approach to study the thermal evolution of (100) hydrogen-induced platelets (HIPs) in silicon. The HIPs are modelled by 10 nm long planar defects in a periodically repeated crystalline model system containing are stabilized by saturating the resulting surface dangling bonds with hydrogen atoms. The time evolution of the defects is studied by finite-temperature MD using the Learn On The Fly (LOTF) technique. This hybrid scheme allows us to perform accurate density-functional-tight-binding (DFTB) force calculations only on the chemically reactive platelet zone, while the surrounding silicon crystal is described by the Stillinger-Weber (SW) classical potential. Reliable dynamical trajectories are obtained by choosing the DFTB zone in a way which minimizes the errors on the atomic forces

Atomically Smooth Stress-Corrosion Cleavage of a Hydrogen-Implanted Crystal

Abstract: We present a quantum-accurate multiscale study of how hydrogen-filled discoidal "platelet'' defects grow inside a silicon crystal. Dynamical simulations of a 10-nm-diameter platelet reveal that H-2 molecules form at its internal surfaces, diffuse, and dissociate at its perimeter, where they both induce and stabilize the breaking up of highly stressed silicon bonds. A buildup of H-2 internal pressure is neither needed for nor allowed by this stress-corrosion growth mechanism, at odds with previous models. Slow platelet growth up to micrometric sizes is predicted as a consequence, making atomically smooth crystal cleavage possible in implantation experiments

Nucleic acid and nucleotide-mediated synthesis of inorganic nanoparticles

Since the advent of practical methods for achieving DNA metallization, the use of nucleic acids as templates for the synthesis of inorganic nanoparticles (NPs) has become an active area of study. It is now widely recognized that nucleic acids have the ability to control the growth and morphology of inorganic NPs. These biopolymers are particularly appealing as templating agents as their ease of synthesis in conjunction with the possibility of screening nucleotide composition, sequence and length, provides the means to modulate the physico-chemical properties of the resulting NPs. Several synthetic procedures leading to NPs with interesting photophysical properties as well as studies aimed at rationalizing the mechanism of nucleic acid-templated NP synthesis are now being reported. This progress article will outline the current understanding of the nucleic acid-templated process and provides an up to date reference in this nascent field