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A density functional theory approach is employed to investigate poly-3-hexylthiophene (P3HT) interfaced with both a semiconducting and metallic carbon nanotube (CNT). For the semiconducting CNT, a type-II heterojunction can form, making such an interface desirable as a photovoltaic heterojunction. In contrast, with the metallic CNT, substantial charge(More)
Explicit integrators for real-time propagation of time-dependent Kohn-Sham equations are compared regarding their suitability for performing large-scale simulations. Four algorithms are implemented and assessed for both stability and accuracy within a plane-wave pseudopotential framework, employing the adiabatic approximation to the exchange-correlation(More)
Advancement in high-performance computing allows us to calculate properties of increasingly complex materials with unprecedented accuracy. At the same time, to take full advantage of modern leadership-class supercomputers, the calculations need to scale well on hundreds of thousands of processing cores. We demonstrate such high scalability of our recently(More)
In the quest to harness solar energy for power generation, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small-molecule activation, and biologically inspired photosynthetic systems. [1] In contrast, the direct collection of heat from sunlight has received much less diversified(More)
We show that atomistic first-principles calculations based on real-time propagation within time-dependent density functional theory are capable of accurately describing electronic stopping of light projectile atoms in metal hosts over a wide range of projectile velocities. In particular, we employ a plane-wave pseudopotential scheme to solve time-dependent(More)
Quantum mechanical electronic structure calculations are playing an ever-expanding role in advancing nanotechnology as well as in advancing our understanding and design of new functional materials. Recent research utilizing quantum mechanical electronic structure calculations is helping to improve upon our understanding of existing nanomaterials-and predict(More)
Role of exchange in density-functional theory for weakly interacting systems: Quantum Monte Carlo analysis of electron density and interaction energy. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly(More)
Motivated by recent experiments, we investigate how NO3-SWNT interactions become energetically favorable with varying oxidation state of a single-walled carbon nanotube (SWNT) using first-principles calculations. Chemisorption becomes less endothermic with respect to physisorption when the SWNT oxidation state is elevated. Importantly, the dissociative(More)
The interfacial charge-transfer mechanism of the P3HT/fullerene photovoltaic heterojunction is elucidated using density functional theory calculations. Our findings indicate that an efficient adiabatic electron transfer is highly probable due to the presence of an extended electronic state that has a significant probability distribution across the interface(More)
Caught in the light: The fulvalene diruthenium complex shown on the left side of the picture captures sun light, causing initial Ru-Ru bond rupture to furnish a long-lived triplet biradical of syn configuration. This species requires thermal activation to reach a crossing point (middle) into the singlet manifold on route to its thermal storage isomer on the(More)