Yosuke Kanai

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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)
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)
A recently proposed approach, called "string method," allows us to find minimum energy pathways connecting two metastable states of a system [W. E et al., Phys. Rev. B 66, 052301 (2002)]. So far this approach has been only used with empirical force field parametrizations of the atomic potential energy surface or in the context of macroscopic continuum(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)
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)
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)
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)
We have used scanning tunneling microscopy, Auger electron spectroscopy, and density functional theory calculations to investigate thermal and photoinduced structural transitions in (fulvalene)tetracarbonyldiruthenium molecules (designed for light energy storage) on a Au(111) surface. We find that both the parent complex and the photoisomer exhibit striking(More)