arXiv subjects

Jeremy W. Nicklas

Publications and source records attributed to Jeremy W. Nicklas.

3 recordsLinked to original sources

arXiv2017

Ab initio based empirical potential applied to tungsten at high pressure

Density-functional theory forces, stresses and energies comprise a database from which the optimal parameters of a spline-based empirical potential combining Stillinger-Weber and modified embedded-atom forms are determined. Accuracy of the potential is demonstrated by predictions of ideal shear, stacking fault, vacancy migration, elastic constants and phonons all between 0 and 100 GPa. Consistency with existing models and experiments is demonstrated by application to screw dislocation core structure and deformation twinning in a tungsten nanorod. Lastly, the potential is used to study the high-pressure bcc to fcc phase transition.

cond-mat.mtrl-sci↗

arXiv2010

Band offsets of semiconductor heterostructures: a hybrid density functional study

We demonstrate the accuracy of the hybrid functional HSE06 for computing band offsets of semiconductor alloy heterostructures. The highlight of this study is the computation of conduction band offsets with a reliability that has eluded standard density functional theory. A high-quality special quasirandom structure models an infinite random pseudobinary alloy for constructing heterostructures along the (001) growth direction. Our excellent results for a variety of heterostructures establish HSE06's relevance to band engineering of high-performance electrical and optoelectronic devices.

cond-mat.mtrl-sci↗

arXiv2010

Accurate Ab-initio Predictions of III-V Direct-Indirect Band Gap Crossovers

We report the compositional dependence of the electronic band structure for a range of III-V alloys. Density functional theory with the PBE functional is insufficient to mimic the electronic gap energies at different symmetry points of the Brillouin zone. The HSE hybrid functional with screened exchange accurately reproduces the experimental band gaps and, more importantly, the alloy concentration of the direct-indirect gap crossovers for the III-V alloys studied here: AlGaAs, InAlAs, AlInP, InGaP, and GaAsP.

cond-mat.mtrl-sci↗