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Lie symmetry

Takeshi Iwasa, Takaaki Sato, Makito Takagi, Min Gao, Andrey Lyalin, Masato Kobayashi, Ken-Ichi Shimizu, Satoshi Maeda, Tetsuya Taketsugu
In nanocatalysis a growing attention has recently been given to investigation of energetically low-lying structural isomers of atomic clusters, because some isomers can demonstrate better catalytic activity than the most stable structures. In this study, we present a comparative investigation of a catalytic activity for NO dissociation of a pair of the energetically degenerated isomers of Cu13 cluster having C2 and Cs symmetries. It is shown that although these isomers have similar structural, electronic, and optical properties, they can possess very different catalytic activity...
December 12, 2018: Journal of Physical Chemistry. A
G Lebreton, C Géminard, F Lapraz, S Pyrpassopoulos, D Cerezo, P Spéder, E M Ostap, S Noselli
The emergence of asymmetry from an initially symmetrical state is a universal transition in nature. Living organisms show asymmetries at the molecular, cellular, tissular, and organismal level. However, whether and how multilevel asymmetries are related remains unclear. In this study, we show that Drosophila myosin 1D (Myo1D) and myosin 1C (Myo1C) are sufficient to generate de novo directional twisting of cells, single organs, or the whole body in opposite directions. Directionality lies in the myosins' motor domain and is swappable between Myo1D and Myo1C...
November 23, 2018: Science
Lee M Thompson
Broken symmetry solutions-solutions to the independent particle model that do not obey all symmetries required by the Hamiltonian-have attracted significant interest for capturing multireference properties with mean-field scaling. However, identification and optimization of broken-symmetry solutions is difficult owing to the non-linear nature of the self-consistent field (SCF) equations, particularly for solutions belonging to low-symmetry subgroups and where multiple broken symmetry solutions are sought. Linearization of SCF solution space results in the Lie algebra, which this work utilizes as a framework for elucidation of the set of solutions that exist at the desired symmetry...
November 21, 2018: Journal of Chemical Physics
Christine M Aikens
Ligand-protected noble metal nanoclusters are of interest for their potential applications in areas such as bioimaging, catalysis, photocatalysis, and solar energy harvesting. These nanoclusters can be prepared with atomic precision, which means that their stoichiometries can be ascertained; the properties of these nanoclusters can vary significantly depending on the exact stoichiometry and geometric structure of the system. This leads to important questions such as: What are the general principles that underlie the physical properties of these nanoclusters? Do these principles hold for all systems? What properties can be "tuned" by varying the size and composition of the system? In this Account, we describe research that has been performed to analyze the electronic structure, linear optical absorption, and excited state dynamics of thiolate-stabilized noble metal nanoclusters...
November 16, 2018: Accounts of Chemical Research
Olga Yu Vassilyeva, Katerina V Kasyanova, Vladimir N Kokozay, Brian W Skelton
The title compound, [CoCd(C9 H10 NO2 )3 Cl2 ]·H2 O, is a solvatomorph of the corresponding hemihydrate recently published by us [Nesterova et al. (2018 ▸). Appl. Cat. A , 560 , 171-184]. The current structure reveals different cell parameters and space group compared with the published one while both are monoclinic with almost the same cell volume. The title compound is formed of discrete neutral dinuclear mol-ecules with no crystallographically imposed symmetry and water mol-ecules of crystallization. The overall geometry about the cobalt(III) ion is octa-hedral with an N3 O3 environment; each ligand acts as a meridional ONO donor...
November 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
Álvaro Valdés, Orlando Carrillo-Bohórquez, Rita Prosmiti
We implemented a systematic procedure for treating the quantal rotations by including all translational and vibrational degrees of freedom for any triatomic bent molecule in any embedded or confined environment, within the MCTDH framework. Fully coupled quantum treatments were employed to investigate unconventional properties in nanoconfined molecular systems. In this way, we facilitate a complete theoretical analysis of the underlying dynamics that enables us to compute the energy levels and the nuclear spin isomers of a single water molecule trapped in a C60 fullerene cage...
November 20, 2018: Journal of Chemical Theory and Computation
Charlotte Sleight, Massimo Taronna
We present a no-go result on consistent Noether interactions among higher-spin gauge fields on anti-de Sitter space-times. We show that there is a nonlocal obstruction at the classical level to consistent interacting field theory descriptions of massless higher-spin particles that are described in the free limit by the free Fronsdal action, under the assumption that such theories arise from the gauging of a global higher-spin symmetry. Our result suggests that the Fronsdal program for introducing interactions among higher-spin gauge fields cannot be completed without introducing new guiding principles, which could potentially lie beyond the framework of classical field theory...
October 26, 2018: Physical Review Letters
Mark P Bogers, Tomáš Brauner
We use Lie-algebraic arguments to classify Lorentz-invariant theories of massless interacting scalars that feature coordinate-dependent redundant symmetries of the Galileon type. We show that such theories are determined, up to a set of low-energy effective couplings, by specifying an affine representation of the Lie algebra of physical, nonredundant internal symmetries and an invariant metric on its target space. This creates an infinite catalog of theories relevant for both cosmology and high-energy physics thanks to their special properties such as enhanced scaling of scattering amplitudes in the soft limit...
October 26, 2018: Physical Review Letters
Jan Šmydke, Csaba Fábri, János Sarka, Attila G Császár
Rotational-vibrational states up to 3200 cm-1, beyond the highest-lying stretching fundamental, are computed variationally for the vinyl radical (VR), H2Cβ[double bond, length as m-dash]CαH, and the following deuterated isotopologues of VR: CH2[double bond, length as m-dash]CD, CHD[double bond, length as m-dash]CH, and CD2[double bond, length as m-dash]CD. The height of the CαH tunneling rocking barrier of VR, partially responsible for the complex nuclear dynamics of VR and its isotopologues, is determined to be 1641 ± 25 cm-1 by the focal-point analysis approach...
November 8, 2018: Physical Chemistry Chemical Physics: PCCP
Max D J Waters, Anders B Skov, Martin A B Larsen, Christian M Clausen, Peter M Weber, Theis I Sølling
Symmetry effects in internal conversion are studied by means of two isomeric cyclic tertiary aliphatic amines in a velocity map imaging (VMI) experiment on the femtosecond timescale. It is demonstrated that there is a delicate structural dependence on when coherence is preserved after the transition between the 3p and 3s Rydberg states. N-Methyl morpholine (NMM) shows unambiguous preserved coherence, consistent with previous work, which is decidedly switched off by the repositioning of oxygen within the ring...
November 6, 2018: Physical Chemistry Chemical Physics: PCCP
Kenny Choo, Giuseppe Carleo, Nicolas Regnault, Titus Neupert
Artificial neural networks have been recently introduced as a general ansatz to represent many-body wave functions. In conjunction with variational Monte Carlo calculations, this ansatz has been applied to find Hamiltonian ground states and their energies. Here, we provide extensions of this method to study excited states, a central task in several many-body quantum calculations. First, we give a prescription that allows us to target eigenstates of a (nonlocal) symmetry of the Hamiltonian. Second, we give an algorithm to compute low-lying excited states without symmetries...
October 19, 2018: Physical Review Letters
C G Wang, Z Li, J Yang, L Y Xing, G Y Dai, X C Wang, C Q Jin, R Zhou, Guo-Qing Zheng
A magnetic order can be completely suppressed at zero temperature (T), by doping carriers or applying pressure, at a quantum critical point, around which physical properties change drastically. However, the situation is unclear for an electronic nematic order that breaks rotation symmetry. Here, we report nuclear magnetic resonance studies on NaFe_{1-x}Co_{x}As where magnetic and nematic transitions are well separated. The nuclear magnetic resonance spectrum is sensitive to inhomogeneous magnetic fields in the vortex state, which is related to London penetration depth λ_{L} that measures the electron mass m^{*}...
October 19, 2018: Physical Review Letters
Daniela Rolf, Christian Lotze, Constantin Czekelius, Benjamin W Heinrich, Katharina J Franke
The magnetic properties of metal-organic complexes are strongly influenced by conformational changes in the ligand. The flexibility of Fe-tetra-pyridyl-porphyrin molecules leads to different adsorption configurations on a Au(111) surface. By combining low-temperature scanning tunneling spectroscopy and atomic force microscopy, we resolve a correlation of the molecular configuration with different spin states and magnitudes of magnetic anisotropy. When the macrocycle exhibits a laterally undistorted saddle shape, the molecules lie in a S = 1 state with axial anisotropy arising from a square-planar ligand field...
November 15, 2018: Journal of Physical Chemistry Letters
D Louis, D Lacour, M Hehn, V Lomakin, T Hauet, F Montaigne
Metamaterials, tunable artificial materials, are useful playgrounds to investigate magnetic systems. So far, artificial Ising spin systems have revealed features such as emergent magnetic monopoles1,2 and charge fragmentation3 . Here we present a metasystem composed of a lattice of dipolarly coupled nanomagnets. The magnetic spin of each nanomagnet is constrained to lie along a body diagonal, which yields four possible spin states. We show that the magnetic ordering of this metasystem (antiferromagnetic, ferromagnetic or spin ice like) is determined by the spin states orientation relative to the underlying lattice...
October 29, 2018: Nature Materials
Ruben Stienstra, Walter D van Suijlekom
We give an operator-algebraic interpretation of the notion of an ideal generated by the unbounded operators associated with the elements of the Lie algebra of a Lie group that implements the symmetries of a quantum system. We use this interpretation to establish a link between Rieffel induction and the implementation of a local Gauss law in lattice gauge theories similar to the method discussed by Kijowski and Rudolph (J Math Phys 43:1796-1808, 2002; J Math Phys 46:032303, 2004).
2018: Letters in Mathematical Physics
M Stefanou, H J Chandler, B Mignolet, E Williams, S A Nanoh, J O F Thompson, F Remacle, R Schaub, E E B Campbell
Gas phase photoelectron spectroscopy (Rydberg Fingerprint Spectroscopy), TDDFT calculations and low temperature STM studies are combined to provide detailed information on the properties of the diffuse, low-lying Rydberg-like SAMO states of isolated Li@C60 endohedral fullerenes. The presence of the encapsulated Li is shown by the calculations to produce a significant distortion of the lowest-lying S- and P-SAMOs that is dependent on the position of the Li inside the fullerene cage. Under the high temperature conditions of the gas phase experiments, the Li is mobile and able to access different positions within the cage...
October 24, 2018: Nanoscale
T C Harris, E M Sevick, D R M Williams
Interlocked molecules exhibit structural isomerization that is different from that of molecules whose connectedness is solely through covalent bonds. A mechanical bond, or the interlocking of components, provides a rich conformational landscape. The ability of synthetic chemists to design directional motion between these mechanical conformers suggests mechanical bonds as building blocks in the design of synthetic molecular motors and machines. Here we examine the complexity of mechanical conformers of radial catenanes with n anisotropically repulsive rings (coined "keyrings") threaded onto a single central ring for n ≤ 10...
November 15, 2018: Journal of Physical Chemistry. A
Geetanjali Giri, Suryoday Prodhan, Y Anusooya Pati, S Ramasesha
There is a resurgence of interest in the electronic structure of perylene for its applications in molecular devices such as organic photovoltaics and organic light-emitting diodes. In this study, we have obtained the low-lying singlet states of perylene by exactly solving the Parisar-Parr-Pople model Hamiltonian of this system with 20 sites and 20 electrons in the VB basis where dimensionality is ∼5.92 billion. The triplet states of perylene are obtained using a DMRG scheme with symmetry adaptation. The one- and two-photon states are very close in energy ∼3...
November 1, 2018: Journal of Physical Chemistry. A
Guo-Jin Cao
Recently, the T-Hg(ii)2 -A base pair containing two equivalents of Hg(ii) has been prepared and characterized experimentally, which implies that there might exist considerable stable metal-mediated base pairs holding two neighbouring metal centers. Here we report a quantum chemical study on geometries, electronic structures, and bonding of various G2 Cu2 4+ (G = guanine) isomers including one di-copper(i) unit. Different density functional methods [Becke 3-parameter-Lee-Yang-Parr, Perdew-Becke-Ernzerhof, Becke-Perdew, Density Functional Theory with Dispersion Corrections (DFT-D)] assign ambiguous relative energies to these isomers with the singlet and triplet states...
October 14, 2018: Journal of Chemical Physics
Yukio Watanabe
In the calculations of tetragonal BaTiO3 , some exchange-correlation (XC) energy functionals such as local density approximation (LDA) have shown good agreement with experiments at room temperature (RT), e.g., spontaneous polarization ( P S ), and superiority compared with other XC functionals. This is due to the error compensation of the RT effect and, hence, will be ineffective in the heavily strained case such as domain boundaries. Here, ferroelectrics under large strain at RT are approximated as those at 0 K because the strain effect surpasses the RT effects...
May 21, 2018: Journal of Chemical Physics
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