arXiv subjects

H. Ustunel

Publications and source records attributed to H. Ustunel.

3 recordsLinked to original sources

arXiv2009

High-capacity hydrogen storage by metallized graphene

First-principles plane wave calculations predict that Li can be adsorbed on graphene forming a uniform and stable coverage on both sides. A significant part of the electronic charge of the Li-$2s$ orbital is donated to graphene and is accommodated by its distorted $π^*$-bands. As a result, semimetallic graphene and semiconducting graphene ribbons change into good metals. It is even more remarkable that Li covered graphene can serve as a high-capacity hydrogen storage medium with each adsorbed Li absorbing up to four H$_2$ molecules amounting to a gravimetric density of 12.8 wt%.

cond-mat.mes-hall↗

arXiv2004

Modelling a suspended nanotube oscillator

We present a general study of oscillations in suspended one-dimensional elastic systems clamped at each end, exploring a wide range of slack (excess length) and downward external forces. Our results apply directly to recent experiments in nanotube and silicon nanowire oscillators. We find the behavior to simplify in three well-defined regimes which we present in a dimensionless phase diagram. The frequencies of vibration of such systems are found to be extremely sensitive to slack.

cond-mat.mes-hall↗

arXiv2004

Ab initio mechanical response: internal friction and structure of divacancies in silicon

This letter introduces ab initio study of the full activation-volume tensor of crystalline defects as a means to make contact with mechanical response experiments. We present a theoretical framework for prediction of the internal friction associated with divacancy defects and give the first ab initio value for this quantity in silicon. Finally, making connection with defect alignment studies, we give the first unambiguous resolution of the debate surrounding ab initio verification of the ground-state structure of the defect.

cond-mat.mtrl-sci↗