On the Energy Spectrum and Ground-State Properties οf the Decorated Heisenberg Spin Tube

The ground-state properties of decorated Heisenberg spin tubes with nearest- and next-nearest-neighbor antiferromagnetic exchange interactions has been studied using perturbation theory and exact diagonalization technique. The possibility of quantum phase transitions mediated by next-nearest neighbor interactions for these tubes is shown

Ground-state spin of Hubbard ladder model with infinite electron repulsion

We apply perturbation theory and cyclic spin permutation formalism to study the lowest energy states of the infinite-repulsion Hubbard model on n-leg ladders with alternating values of one-site energies α_{i} for neighboring rungs. We establish the "ferromagnetic" character of ladder ground-state at electron densities in the interval 1 - (2n)¯¹ ≤ ρ ≤ 1 and sufficiently large alternation of one-site energies of neighbor rungs of the ladder. We also show the stability of this state against the small deviations of the values of α_{i} in contrast to the case of two-leg ladder formed by weakly interacting neighbor rungs with equal one-site energies

Energy spectrum and thermodynamics of anisotropic spin-1/2 two-leg ladder

We studied the energy spectrum and some finite temperature properties of two-leg spin-1/2 ladder with XXZ interactions in legs and rungs. It is shown that for a strong ferromagnetic interchain interaction, there is a first-order transition between ferromagnetic and nonmagnetic phases. The anisotropic ladder in the magnetic field may have up to four low-temperature maxima in the temperature dependence of specific heat. (c) 2006 Wiley Periodicals, Inc

Ground-State Spin of Hubbard Ladder Model with Infinite Electron Repulsion

We apply perturbation theory and cyclic spin permutation formalism to study the lowest energy states of the infinite-repulsion Hubbard model on n-leg ladders with alternating values of one-site energies αi for neighboring rungs. We establish the "ferromagnetic" character of ladder ground-state at electron densities in the interval 1 -(2n) −1 ≤ ρ ≤ 1 and sufficiently large alternation of one-site energies of neighbor rungs of the ladder. We also show the stability of this state against the small deviations of the values of αi in contrast to the case of two-leg ladder formed by weakly interacting neighbor rungs with equal one-site energies

AMINO ACIDS IDENTIFICATION IN THE HUMAN SKIN BY SPECTRA APPLICATION OF 0,05-1,2 THZ RANGE

Spectra of human skin and tableted preparations of amino acids in 0,05 1,2 THz range are obtained by terahertz spectroscopy method with time resolution. Comparison of the amino acids spectral lines is made for their identification in the skin. It is shown that the following amino acids are the most clearly visible in the skin spectrum: tryptophan, cysteine, alanine, glycine, phenylalanine and histidine. Terahertz spectral lines of the mentioned amino acids are associated with molecules oscillating modes, caused by chemical reactions, hydration processes and molecules conformal changes in the human skin. Determination of amino acids spectral lines and other specific molecules, involved in the metabolic processes of the skin, is necessary for the development of terahertz diagnostic tool with maximum sensitivity and selectivity