Search results for "Fermi"
showing 10 items of 1388 documents
Symmetric logarithmic derivative of Fermionic Gaussian states
2018
In this article we derive a closed form expression for the symmetric logarithmic derivative of Fermionic Gaussian states. This provides a direct way of computing the quantum Fisher Information for Fermionic Gaussian states. Applications ranges from quantum Metrology with thermal states and non-equilibrium steady states with Fermionic many-body systems.
Scattering theory for a class of fermionic Pauli–Fierz models
2004
Abstract The scattering theory for a class of fermionic Pauli–Fierz models is considered. We give a proof of the asymptotic completeness of the dynamics in the case of massive fermions. The result applied to the Hamiltonian of a quantized spin- 1 2 Dirac particle interacting with an external field through a cutoff Yukawa interaction and to the Hamiltonian of a system of finitely many confined particles coupled to a fermionic field with a quadratic interaction.
Search forBs0→μ+μ−andB0→μ+μ−Decays with CDF II
2011
A search has been performed for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays using 7 fb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B{sup 0} candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of {Beta}(B{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 6.0 x 10{sup -9} at 95% confidence level. We observe an excess of B{sub s}{sup 0} candidates. The probability that the background processes alone could produce such an excess or larger is 0.27%. The probability that the combination of background and the expe…
Creating stable Floquet–Weyl semimetals by laser-driving of 3D Dirac materials
2017
Nature Communications 8, 13940 (2017). doi:10.1038/ncomms13940
Vibrational spectra and force constants of symmetric tops
1983
The infrared spectrum of H3SiI in the 800–1050 cm-1 region has been recorded with a resolution of 0·04 cm-1 and rotationally analysed. Features related to the Fermi resonance between v 5 and v 3 + v 6 and to the Coriolis x, y resonance between v 2 and v 5 have been explained, and a set of vibration-rotation parameters for the three bands has been determined by least-squares calculations, σ(J, K) = 9·4 × 10-3 cm-1. The Fermi resonance matrix element |W 356| is found to be 3·7859(7) cm-1 and the vibrational frequencies are v 2 0 = 904·551(1), v 5 0 = 941·0746(8) and (v 3 + v 6)0 = 953·688(3) cm-1. The anharmonicity constant, x 36 = -1·745(9) cm-1, has been determined. Comparison is made with …
Estimation of formamide harmonic and anharmonic modes in the Kohn-Sham limit using the polarization consistent basis sets.
2010
Formamide harmonic and anharmonic frequencies of fundamental vibrations in the gas phase and in several solvents were successfully estimated in the B3LYP Kohn-Sham complete basis set limit (KS CBS). CBS results were obtained by extrapolating a power function (two-parameter formula) to the results calculated with polarization-consistent basis sets. Anharmonic corrections using the second order perturbation treatment (PT2) and hybrid B3LYP functional combined with polarization consistent pc-n (n = 0, 1, 2, 3, 4) and several Pople’s basis sets were analyzed for all fundamental formamide vibrational modes in the gas phase and solution. Solvent effects were modeled within a PCM method. The anhar…
Raman spectroscopy of formic acid and its dimers isolated in low temperature argon matrices
2009
Raman spectroscopy combined with matrix isolation technique was employed to study formic acid monomer and its dimers. Nine fundamentals of the HCOOH monomer were identified. Additionally, the OH torsion overtone is observed and it is engaged in Fermi resonance with the δCOH mode. Several bands of the cyclic (C2h) dimer were identified and assigned. The less stable open form (Cs) of the dimer was also present in the experiment. Three intermolecular modes for the cyclic and one mode for the open dimer were found in the low frequency region. The experimental studies were supported by harmonic and anharmonic DFT calculations.
Photolysis of HCOOH monomer and dimer in solid argon: Raman characterization of in situ formed molecular complexes
2010
Raman spectroscopy combined with the matrix isolation technique was employed to study the 193-nm photodecomposition products of formic acid in an argon matrix. The Raman-active fundamentals belonging to the CO(2) + H(2) and CO + H(2)O photoproducts were assigned. Also, bands due to Fermi resonance between the stretching vibration (nu(1)) and the overtone of the bending mode (2nu(2)) of CO(2) were identified. Both ortho- and para-H(2) molecules were identified from their rotational lines S(0)(1) and S(0)(0), respectively. These bands appeared upon matrix annealing as well as after prolonged photolysis. Additionally, photolysis of FA dimers produces oxalic acid and its secondary photoproducts…
On the shell structure and geometry of monovalent metal clusters
1991
The Huckel model is used to study the electronic structure of monovalent metal clusters. In an fcc cluster the Huckel model gives an estimate to the electronic structure of a free electron cluster. It is shown that the surface faceting of the fcc cluster can destroy the electronic shell structure already when the cluster has about 100 electrons. In the Huckel model the icosahedral structure has smaller total energy than the fcc structures, from which the Wulff construction has the smallest energy already when the cluster has 600 atoms.
Edge-dependent selection rules in magic triangular graphene flakes
2008
The electronic shell and supershell structure of triangular graphene quantum dots has been studied using density functional and tight-binding methods. The density functional calculations demonstrate that the electronic structure close to the Fermi energy is correctly described with a simple tight-binding model, where only the ${p}_{z}$ orbitals perpendicular to the graphene layer are included. The results show that (i) both at the bottom and at the top of the ${p}_{z}$ band, a supershell structure similar to that of free electrons confined in a triangular cavity is seen, (ii) close to the Fermi level, the shell structure is that of free massless particles, (iii) triangles with armchair edge…