Biomedical subjects

P D Haynes

Publications and source records attributed to P D Haynes.

2 recordsLinked to original sources

PubMed2006

Are the structures of twist grain boundaries in silicon ordered at 0 K?

Contrary to previous simulation results on the existence of amorphous intergranular films at high-angle twist grain boundaries (GBs) in elemental solids such as silicon, recent experimental results imply structural order in some high-angle boundaries. With a novel protocol for simulating twist GBs, which allows the number of atoms at the boundary to vary, we have found new low-energy ordered structures. We give a detailed exposition of the results for the simplest boundary. The validity of our results is confirmed by first-principles calculations.

Journal Article↗

PubMed2004

Structural relaxations in electronically excited poly(para-phenylene).

Structural relaxations in electronically excited poly(para-phenylene) are studied using many-body perturbation theory and density-functional-theory methods. A sophisticated description of the electron-hole interaction is required to describe the excitonic energies, but the associated structural relaxations can be obtained quite accurately within a constrained density-functional-theory approach. We find that the structural relaxations in the low-energy excitonic states extend over about eight monomers, leading to an energy reduction of 0.22 eV and a Stokes shift of 0.40 eV.

Journal Article↗