Variational state based on the Bethe ansatz solution and a correlated singlet liquid state in the one-dimensional t-J model

The one-dimensional t-J model is investigated by the variational Monte Carlo method. A variational wave function based on the Bethe ansatz solution is newly proposed, where the spin-charge separation is realized, and a long-range correlation factor of Jastrow-type is included. In most regions of the phase diagram, this wave function provides an excellent description of the ground-state properties characterized as a Tomonaga-Luttinger liquid; Both of the amplitude and exponent of correlation functions are correctly reproduced. For the spin-gap phase, another trial state of correlated singlet pairs with a Jastrow factor is introduced. This wave function shows generalized Luther-Emery liquid behavior, exhibiting enhanced superconducting correlations and exponential decay of the spin correlation function. Using these two variational wave functions, the whole phase diagram is determined. In addition, relations between the correlation exponent and variational parameters in the trial functions are derived.Comment: REVTeX 3.0, 27 pages. 7 figures available upon request ([email protected]). To be published in Phys. Rev. B 5

Behavior of exciton wave scattered by the impurity in a quasi-one dimensional molecular crystal

The behavior of exciton wave scattered by the impurity in a quasi-one dimensional molecular crystal was studied by the Green function method. The scattered wave was found to consist of three components, and their characters were studied in detail. When the impurity level is out of the exciton energy band of host crystal, the two components have the mixed character of hopping and resonance transfer, and the remaining component gives the slate localized around the impurity. When the impurity level is in the exciton band, however, the three components have only the character of resonance transfer and they are all spreading widely through the crystal

Propagation of Frenkel-exciton strongly coupled with phonons in molecular crystals

The propagation of FRENKEL exciton strongly coupled with phonons in molecular crystals is studied. The strong interaction part in the Hamiltonian was removed at first by a canonical transformation. Then the time-dependent perturbation theory was applied. Actual calculation is made on a one-dimensional model, and the wave function of the exciton- phonon system is obtained. With this wave function, the properties of exciton such as the probability-density at each lattice-site, the diffusion coefficient and its temperature- dependence, and the lattice distortion by the exciton-phonon interaction are computed

Fonction de green de l’exciton couplé avec les phonons dans les cristaux moléculaires

On détermine la fonction de Green de l’exciton de Frenkel mobile, couplé avec les phonons optiques dans les cristaux moléculaires, en tenant compte des termes de résonance et de « saut » non cohérent dans l’Hamiltonian. Dans le développement en série des perturbations, on inclut — dans le cadre de certaines limites — un nombre infini de termes; on fait aussi apparaître explicitement les effets de diffusions multiples. Dans la discussion, le premier travail est confronté à celui d’autres auteurs

Les constantes de force de la vibration moléculaire de SiO4(CH 3)4

Nous avons développé les équations séculaires donnant les fréquences fondamentales de SiO4(CH 3)4. Alors, en tenant compte des résultats expérimentaux, nous avons déterminé les valeurs des constantes de force des silicates telles que :$$ Une comparaison est faite avec les valeurs obtenues par d'autres chercheurs

The intermolecular potential of the ethylene dimer

The intermolecular potential of the ethylene dimer was calculated by using the perturbation theory developed by Murrell, Randié, Williams and Shaw including the exchange energy. The CNDO/2 wave functions and Clementi Atomic Orbitals were used for the electronic states of each molecule. The calculated value of the dissociation energy at the intermolecular distance of 4.5 Å in parallel orientation is 17.9 × 10-3 eV, and at the distance of 5.4 Å in perpendicular orientation it is 15.3 × 10-3 eV, and they are in better agreement with experiments than those previously calculated

A study of the electric conductivity of TNCQ, complex by the coherent potential approximation

The electric conductivity and its temperature-dependence of TCNQ complex salts are studied, employing the coherent potential approximation (CPA). Calculated values of the electric conductivity of TEA (TCNQ)2 at 23 °C and its activation energy are 4.7 or 5.0 mho cm-1 and 0.15 or 0.13 eV respectively

Environmental sex determination in the branchiopod crustacean Daphnia magna: deep conservation of a Doublesex gene in the sex-determining pathway

Sex-determining mechanisms are diverse among animal lineages and can be broadly divided into two major categories: genetic and environmental. In contrast to genetic sex determination (GSD), little is known about the molecular mechanisms underlying environmental sex determination (ESD). The Doublesex (Dsx) genes play an important role in controlling sexual dimorphism in genetic sex-determining organisms such as nematodes, insects, and vertebrates. Here we report the identification of two Dsx genes from Daphnia magna, a freshwater branchiopod crustacean that parthenogenetically produces males in response to environmental cues. One of these genes, designated DapmaDsx1, is responsible for the male trait development when expressed during environmental sex determination. The domain organization of DapmaDsx1 was similar to that of Dsx from insects, which are thought to be the sister group of branchiopod crustaceans. Intriguingly, the molecular basis for sexually dimorphic expression of DapmaDsx1 is different from that of insects. Rather than being regulated sex-specifically at the level of pre–mRNA splicing in the coding region, DapmaDsx1 exhibits sexually dimorphic differences in the abundance of its transcripts. During embryogenesis, expression of DapmaDsx1 was increased only in males and its transcripts were primarily detected in male-specific structures. Knock-down of DapmaDsx1 in male embryos resulted in the production of female traits including ovarian maturation, whereas ectopic expression of DapmaDsx1 in female embryos resulted in the development of male-like phenotypes. Expression patterns of another D. magna Dsx gene