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Attraction symmetry

Nelly Bonifaci, Zhiling Li, Jussi Eloranta, Steven L Fiedler
The interaction potentials of the He(*)(2) excimer, in the a (3)Σu, b (3)Πg, c (3)Σg , and d (3)Σu electronic states with a ground state helium atom are presented. The symmetry of the interaction potentials closely follows the excimer Rydberg electron density with pronounced short-range minima appearing along the nodal planes of the Rydberg orbital. In such cases, a combination of the electrostatic short-range attraction combined with Pauli repulsion leads to the appearance of unusual long-range maxima in the potentials...
October 26, 2016: Journal of Physical Chemistry. A
Christina Bagwill, Christa Anderson, Elizabeth Sullivan, Varun Manohara, Prithvi Murthy, Charles C Kirkpatrick, Apryll M Stalcup, Michael Adam Lewis
A computational study aimed at accurately predicting the strength of the anion-π binding of substituted benzenes is presented. The anion-π binding energies (Ebind) of 37 substituted benzenes, and the parent benzene, with chloride or bromide were investigated at the MP2(full)/6-311++G** level of theory. In addition, energy decomposition analysis was performed on 27 selected chloride-arene complexes via Symmetry Adapted Perturbation Theory (SAPT), using the SAPT2+ approach. Initial efforts aimed to correlate the anion-π Ebind values with the sum of the Hammett constants σp (Σσp) or σm (Σσm), as done by others...
October 25, 2016: Journal of Physical Chemistry. A
Laurent Pedesseau, Daniel Sapori, Boubacar Traore, Roberto Robles, Hong-Hua Fang, Maria Antonietta Loi, Hsinhan Tsai, Wanyi Nie, Jean-Christophe Blancon, Amanda Neukirch, Sergei Tretiak, Aditya D Mohite, Claudine Katan, Jacky Even, Mikaël Kepenekian
Layered halide hybrid organic-inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells and revisited for light-emitting devices. In this review, we combine classical solid-state physics concepts with simulation tools based on density functional theory to overview the main features of the optoelectronic properties of layered HOP...
October 24, 2016: ACS Nano
Michael G Sommer, Yvonne Rechkemmer, Lisa Suntrup, Stephan Hohloch, Margarethe van der Meer, Joris van Slageren, Biprajit Sarkar
The azido ligand is widely used in coordination chemistry both as a ligand and as a metal-bound reactant. Its role as a bridge for magnetic exchange coupling has attracted a lot of attention in polynuclear metal complexes. However, only a very limited number of complexes are known in which a single azide anion, particularly in the μ1,1-mode, is the only unsupported connection between two metal centers. We present here a series of copper(ii)-azido complexes with amine anchored, triazole-based tripodal ligands containing varying substituents...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Justin K Mogilski, Lisa L M Welling
Sexual dimorphism, symmetry, and coloration in human faces putatively signal information relevant to mate selection and reproduction. Although the independent contributions of these characteristics to judgments of attractiveness are well established, relatively few studies have examined whether individuals prioritize certain features over others. Here, participants (N = 542, 315 female) ranked six sets of facial photographs (3 male, 3 female) by their preference for starting long- and short-term romantic relationships with each person depicted...
October 17, 2016: Human Nature: An Interdisciplinary Biosocial Perspective
Naiyin Yu, Abhijit Ghosh, Michael F Hagan
We use computer simulations and simple theoretical models to analyze the morphologies that result when rod-like particles end-attach onto a curved surface, creating a finite-thickness monolayer aligned with the surface normal. This geometry leads to two forms of frustration, one associated with the incompatibility of hexagonal order on surfaces with Gaussian curvature, and the second reflecting the deformation of a layer with finite thickness on a surface with non-zero mean curvature. We show that the latter effect leads to a faceting mechanism...
October 17, 2016: Soft Matter
Chandan K Mishra, A K Sood, Rajesh Ganapathy
The monomer surface mobility is the single most important parameter that decides the nucleation density and morphology of islands during thin-film growth. During template-assisted surface growth in particular, low surface mobilities can prevent monomers from reaching target sites and this results in a partial to complete loss of nucleation control. Whereas in atomic systems a broad range of surface mobilities can be readily accessed, for colloids, owing to their large size, this window is substantially narrow and therefore imposes severe restrictions in extending template-assisted growth techniques to steer their self-assembly...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Y Zhang, J J Lee, R G Moore, W Li, M Yi, M Hashimoto, D H Lu, T P Devereaux, D-H Lee, Z-X Shen
Superconductivity originates from pairing of electrons near the Fermi energy. The Fermi surface topology and pairing symmetry are thus two pivotal characteristics of a superconductor. Superconductivity in one monolayer (1 ML) FeSe thin film has attracted great interest recently due to its intriguing interfacial properties and possibly high superconducting transition temperature over 65 K. Here, we report high-resolution measurements of the Fermi surface and superconducting gaps in 1 ML FeSe using angle-resolved photoemission spectroscopy...
September 9, 2016: Physical Review Letters
Elad Shamriz, Nir Dror, Boris A Malomed
We report results of an analysis of the spontaneous symmetry breaking (SSB) in a basic (actually, simplest) model that is capable of producing the SSB phenomenology in a one-dimensional setting. It is based on the Gross-Pitaevskii-nonlinear Schrödinger equation with the cubic self-attractive term and a double-well potential built as an infinitely deep potential box split by a narrow (δ functional) barrier. The barrier's strength ɛ is the single free parameter of the scaled form of the model. It may be implemented in atomic Bose-Einstein condensates and nonlinear optics...
August 2016: Physical Review. E
A Trenkwalder, G Spagnolli, G Semeghini, S Coop, M Landini, P Castilho, L Pezzè, G Modugno, M Inguscio, A Smerzi, M Fattori
Symmetry-breaking quantum phase transitions play a key role in several condensed matter, cosmology and nuclear physics theoretical models1-3. Its observation in real systems is often hampered by finite temperatures and limited control of the system parameters. In this work we report for the first time the experimental observation of the full quantum phase diagram across a transition where the spatial parity symmetry is broken. Our system is made of an ultra-cold gas with tunable attractive interactions trapped in a spatially symmetric double-well potential...
September 2016: Nature Physics
J Koivisto, M-J Dalbe, M J Alava, S Santucci
Crack propagation is tracked here with Digital Image Correlation analysis in the test case of two cracks propagating in opposite directions in polycarbonate, a material with high ductility and a large Fracture Process Zone (FPZ). Depending on the initial distances between the two crack tips, one may observe different complex crack paths with in particular a regime where the two cracks repel each other prior to being attracted. We show by strain field analysis how this can be understood according to the principle of local symmetry: the propagation is to the direction where the local shear - mode KII in fracture mechanics language - is zero...
2016: Scientific Reports
Lloyd L Lee, Giuseppe Pellicane
In order to design a flexible molecular model that mimics the chemical moieties of a polyatomic molecule, we propose the 'composite-sphere' model that can assemble the essential elements to produce the structure of the target molecule. This is likened to the polymerization process where monomers assemble to form the polymer. The assemblage is built into the pair interaction potentials which can 'react' (figuratively) with selective pieces into various bonds. In addition, we preserve the spherical symmetries of the individual pair potentials so that the isotropic Ornstein-Zernike equation (OZ) for multi-component mixtures can be used as a theoretical framework...
October 19, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yuri Martínez-Ratón, Miguel González-Pinto, Enrique Velasco
We theoretically study the phase behaviour of monolayers of hard rod-plate mixtures using a fundamental-measure density functional in the restricted-orientation (Zwanzig) approximation. Particles can rotate in 3D but their centres of mass are constrained to be on a flat surface. In addition, we consider both species to be subject to an attractive potential proportional to the particle contact area on the surface and with adsorption strengths that depend on the species type. Particles have board-like shape, with sizes chosen using a symmetry criterion: same volume and same aspect ratio κ...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
Shengxi Huang, Yuki Tatsumi, Xi Ling, Huaihong Guo, Ziqiang Wang, Garrett Watson, Alexander A Puretzky, David B Geohegan, Jing Kong, Ju Li, Teng Yang, Riichiro Saito, Mildred S Dresselhaus
Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C2h(3) space group. Investigating the in-plane optical anisotropy, including the electron-photon and electron-phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics...
September 27, 2016: ACS Nano
Piotr Matczak
For a series of five model complexes composed of a singlet SnX2 molecule (X = H, F, Cl, Br, I) and a benzene molecule, the first-principles calculations of their energetics and the analysis of their electron density topology have been performed. The CCSD(T)/CBS interaction energy between SnX2 and C6H6 fall into the range between -10.0 and -11.2 kcal/mol, which indicates that the complexes are rather weakly bound. The relevant role of electrostatic and dispersion contributions to the interaction energy between SnX2 and C6H6 is highlighted in the results obtained from the symmetry-adapted perturbation theory (SAPT)...
September 2016: Journal of Molecular Modeling
Dominic J Glover, Douglas S Clark
The ability to assemble molecules into supramolecular architectures of controllable size and symmetry is a long sought after goal of nanotechnology and material engineering. Proteins are particularly attractive for molecular assembly due to their inherent molecular recognition and self-assembly capabilities. Advances in the computational prediction of protein folding and quaternary assembly have enabled the design of proteins that self-assemble into complex yet predictable shapes. These protein nanostructures are opening new possibilities in biomaterials, metabolic engineering, molecular delivery, tissue engineering, and a plethora of nanomaterials...
July 27, 2016: ACS Central Science
Dieter Sorsche, Markus Schaub, Frank W Heinemann, Johannes Habermehl, Susanne Kuhri, Dirk Guldi, Julien Guthmuller, Sven Rau
The synthesis and characterization of a mixed metal ruthenium(ii)/gold(iii) complex bridged by tetrapyridophenazine (tpphz) are described. It is isostructural and isoelectronic to the well-known photocatalysts with palladium(ii) or platinum(ii). Concentration dependent (1)H-NMR spectroscopy and XRD studies show that the electrostatic repulsion between the gold(iii) moieties exceeds the attractive π-stacking interaction. Theoretical calculations based on the new structural data confirm an increased positive charge on the bridging ligand as well as significantly altered orbital symmetry as compared to the previously investigated palladium(ii) complex...
August 9, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Masato Watanabe, Seishi Abe
Fe3O4 has been known to have attractive physical properties for spintronic applications such as half-metallicity, however, its complicated magnetism has yet to be elucidated fully. We investigated the sputtered polycrystalline Fe3O4 thin film in which Ge was added for stabilization of the spinal structure. From X-ray photoelectron and Raman spectroscopies, major part of added Ge is found to be quadrivalent and considered to be incorporated in the spinel structure. Out-of-plane alignment of the local moment was confirmed by conversion electron Mössbauer spectroscopy and magnetization measurements with an applied field up to 70 kOe also support it...
March 2016: Journal of Nanoscience and Nanotechnology
Junwen Li, Paul M Haney
Organic-inorganic halide CH3NH3PbI3 solar cells have attracted enormous attention in recent years due to their remarkable power conversion efficiency. When inversion symmetry is broken, these materials should exhibit interesting spin-dependent properties as well, owing to their strong spin-orbit coupling. In this work, we consider the spin-dependent optical response of CH3NH3PbI3. We first use density functional theory to compute the ballistic spin current generated by absorption of unpolarized light. We then consider diffusive transport of photogenerated charge and spin for a thin CH3NH3PbI3 layer with a passivated surface and an Ohmic, non-selective contact...
April 15, 2016: Physical Review. B
Peter J Chung, Chaeyeon Song, Joanna Deek, Herbert P Miller, Youli Li, Myung Chul Choi, Leslie Wilson, Stuart C Feinstein, Cyrus R Safinya
Tau, an intrinsically disordered protein confined to neuronal axons, binds to and regulates microtubule dynamics. Although there have been observations of string-like microtubule fascicles in the axon initial segment (AIS) and hexagonal bundles in neurite-like processes in non-neuronal cells overexpressing Tau, cell-free reconstitutions have not replicated either geometry. Here we map out the energy landscape of Tau-mediated, GTP-dependent 'active' microtubule bundles at 37 °C, as revealed by synchrotron SAXS and TEM...
2016: Nature Communications
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