There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

We present a parameter-free method for an accurate determination of long-range van der Waals interactions from mean-field electronic structure calculations. Our method relies on the summation of interatomic C6 coefficients, derived from the electron density of a molecule or solid and accurate reference data for the free atoms. The mean absolute error in the C6 coefficients is 5.5% when compared to accurate experimental values for 1225 intermolecular pairs, irrespective of the employed exchangecorrelation functional. We show that the effective atomic C6 coefficients depend strongly on the bonding environment of an atom in a molecule. Finally, we analyze the van der Waals radii and the damping function in the C6R � 6 correction method for density-functional theory calculations.

/pdf/accurate-molecular-van-der-waals-interactions-from-ground-4sgen01nnb.pdf

Accurate molecular van der Waals interactions from ground-state electron density and free-atom reference data

There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

T. Lichtenstein,1 Z. Mamiyev,1,2 C. Braun,3 S. Sanna,4 W. G. Schmidt,3 C. Tegenkamp,1,2 and H. Pfnür1,2,* 1Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany 2Laboratorium für Nanound Quantenengineering (LNQE), Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany 3Theoretische Materialwissenschaften, Universität Paderborn, D-33095 Paderborn, Germany 4Institut für Theoretische Physik, Justus-Liebig-Universität Gießen, Heinrich-Buff-Weg 16, D-35392 Gießen, Germany

Probing quasi-one-dimensional band structures by plasmon spectroscopy

Polytypism driven zero-field splitting of silicon vacancies in 6 H -SiC

The adsorption of single methanol molecules on the lithium niobate (0001) surface, commonly referred to as Z-cut, is investigated using first-principles calculations. It is found that the binding energy for molecular adsorption on the negative surface ($\ensuremath{\sim}$1 eV) is about twice as large as for the positive surface. This difference is related to different bond strengths rather than electrostatics. Depending on the reaction path, lithium extraction from the negative surface may occur. This leads to an additional energy lowering by a few tenths of an eV. Larger energy gains are realized by dissociative adsorption, which is an activated process, however.

/pdf/polarization-dependent-methanol-adsorption-on-lithium-19irka7236.pdf

Polarization-dependent methanol adsorption on lithium niobate Z-cut surfaces

Angle Resolved Photoemission Spectroscopy of the InP(001) surface

The modification of the semiconductor-surface optical response is investigated for the prototypical system of 9,10-phenanthrenequinone adsorbed on Si(001). By means of first-principles calculations we reproduce and explain recently measured reflectance-anisotropy data. The detailed analysis of the optical signal shows that intramolecular $\ensuremath{\pi}\text{\ensuremath{-}}{\ensuremath{\pi}}^{*}$ transitions as well as adsorption-modified Si bulk states contribute to the surface spectrum. The calculations illustrate the sensitivity of optical spectroscopy to molecular adsorption, but demonstrate clearly that a naive interpretation of the spectrum in terms of gas-phase molecular data fails.

Wolf Gero Schmidt

Papers

Probing quasi-one-dimensional band structures by plasmon spectroscopy

Polytypism driven zero-field splitting of silicon vacancies in 6 H -SiC

Polarization-dependent methanol adsorption on lithium niobate Z-cut surfaces

Angle Resolved Photoemission Spectroscopy of the InP(001) surface

Optical response of π -conjugated molecular monolayer adsorbed on the semiconductor Si(001) surface: A first-principles study