1,520 research outputs found
Macroscopic quantum coherence in antiferromagnetic molecular magnets
The macroscopic quantum coherence in a biaxial antiferromagnetic molecular
magnet in the presence of magnetic field acting parallel to its hard anisotropy
axis is studied within the two-sublattice model. On the basis of instanton
technique in the spin-coherent-state path-integral representation, both the
rigorous Wentzel-Kramers-Brillouin exponent and preexponential factor for the
ground-state tunnel splitting are obtained. We find that the quantum
fluctuations around the classical paths can not only induce a new quantum phase
previously reported by Chiolero and Loss (Phys. Rev. Lett. 80, 169 (1998)), but
also have great influnence on the intensity of the ground-state tunnel
splitting. Those features clearly have no analogue in the ferromagnetic
molecular magnets. We suggest that they may be the universal behaviors in all
antiferromagnetic molecular magnets. The analytical results are complemented by
exact diagonalization calculation.Comment: 6 pages, 1 figur
4-Methyl-N-[(Z)-3-(4-methylphenylsulfonyl)-1,3-thiazolidin-2-ylidene]benzenesulfonamide
In the crystal structure of the title compound, C17H18N2O4S3, molecules are connected into centrosymmetric dimers via weak intermolecular C—H⋯π interactions. These dimers are further connected through a series of weak C—H⋯O hydrogen bonds, while futher C—H⋯π interactions involving the phenyl and thiazoline rings are also observed. The thiazolidine ring is twisted from the benzene rings rings by dihedral angles of 79.1 (1) and 85.0 (1)°, while the dihedral angle between two benzene rings is 76.0 (1)°
Comparing standard distribution and its Tsallis form of transverse momenta in high energy collisions
In this paper, the experimental (simulated) transverse momentum spectra of
negatively charged pions produced at mid-rapidity in central nucleus-nucleus
collisions at the Heavy Ion Synchrotron (SIS), Relativistic Heavy Ion Collider
(RHIC), and Large Hadron Collider (LHC) energies obtained by different
collaborations are selected by us to investigate, where a few simulated data
are taken from the results of FOPI Collaboration who uses the IQMD transport
code based on Quantum Molecular Dynamics. A two-component standard distribution
and the Tsallis form of standard distribution are used to fit these data in the
framework of a multisource thermal model. The excitation functions of main
parameters in the two distributions are analyzed. In particular, the effective
temperatures extracted from the two-component standard distribution and the
Tsallis form of standard distribution are obtained, and the relation between
the two types of effective temperatures is studied.Comment: 22 pages, 8 figures. Advances in High Energy Physics, accepte
6,6′-Dimethyl-2,2′-[oxalylbis(azanediyl)]dipyridinium dichloride acetonitrile solvate
In the crystal structure of the title compound, C14H16N4O2
2+·2Cl−·CH3CN, weak intermolecular N—H⋯Cl hydrogen bonds are found between the H atoms bound to the pyridine and amine N atoms and the chloride anions. The asymmetric unit consits of one half cationic molecule which is located on a centre of inversion, one chloride anion in a general position and one half acetonitrile molecule which is located on a twofold axis. Because of symmetry, the C—H hydrogens of the acetonitrile solvent molecule are disordered over two orientations
N-(6-Methyl-2-pyridyl)formamide
The molecule of the title compound, C7H8N2O, is essentially planar with a maximum deviation of 0.0439 (1) Å from the best plane. In the crystal, N—H⋯O hydrogen bonds between self-complementary amide groups join molecules into centrosymmetric dimers
Scaling behaviour and memory in heart rate of healthy human
We investigate a set of complex heart rate time series from healthy human in different behaviour states with the detrended fluctuation analysis and diffusion entropy (DE) method. It is proposed that the scaling properties are influenced by behaviour states. The memory detected by DE exhibits an approximately same pattern after a detrending procedure. Both of them demonstrate the long-range strong correlations in heart rate. These findings may be helpful to understand the underlying dynamical evolution process in the heart rate control system, as well as to model the cardiac dynamic process
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