Effects of nanoscale spatial inhomogeneity in strongly correlated systems

We calculate ground-state energies and density distributions of Hubbard superlattices characterized by periodic modulations of the on-site interaction and the on-site potential. Both density-matrix renormalization group and density-functional methods are employed and compared. We find that small variations in the on-site potential $v_i$ can simulate, cancel, or even overcompensate effects due to much larger variations in the on-site interaction $U_i$. Our findings highlight the importance of nanoscale spatial inhomogeneity in strongly correlated systems, and call for reexamination of model calculations assuming spatial homogeneity.Comment: 5 pages, 1 table, 4 figures, to appear in PR

Density-functionals not based on the electron gas: Local-density approximation for a Luttinger liquid

By shifting the reference system for the local-density approximation (LDA) from the electron gas to other model systems one obtains a new class of density functionals, which by design account for the correlations present in the chosen reference system. This strategy is illustrated by constructing an explicit LDA for the one-dimensional Hubbard model. While the traditional {\it ab initio} LDA is based on a Fermi liquid (the electron gas), this one is based on a Luttinger liquid. First applications to inhomogeneous Hubbard models, including one containing a localized impurity, are reported.Comment: 4 pages, 4 figures (final version, contains additional applications and discussion; accepted by Phys. Rev. Lett.

Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism

We probe the two-scale factor universality hypothesis by evaluating, firstly explicitly and analytically at the one-loop order, the loop quantum corrections to the amplitude ratios for O($N$) $\lambda\phi^{4}$ scalar field theories with rotation symmetry-breaking in three distinct and independent methods in which the rotation symmetry-breaking mechanism is treated exactly. We show that the rotation symmetry-breaking amplitude ratios turn out to be identical in the three methods and equal to their respective rotation symmetry-breaking ones, although the amplitudes themselves, in general, depend on the method employed and on the rotation symmetry-breaking parameter. At the end, we show that all these results can be generalized, through an inductive process based on a general theorem emerging from the exact calculation, to any loop level and physically interpreted based on symmetry ideas.Comment: 17 pages, 3 figure

Predicting Psi-BN: computational insights into its mechanical, electronic, and optical characteristics

Computational materials are pivotal in advancing our understanding of distinct material classes and their properties, offering valuable insights in predicting novel structures and complementing experimental approaches. In this context, Psi-graphene is a stable two-dimensional carbon allotrope composed of 5-6-7 carbon rings theoretically predicted recently. Using density functional theory (DFT) calculations, we explored its boron nitride counterpart's mechanical, electronic, and optical characteristics (Psi-BN). Our results indicate that Psi-BN possesses a band gap of 4.59 eV at the HSE06 level. Phonon calculations and ab initio molecular dynamics simulations demonstrated that this material has excellent structural and dynamic stability. Moreover, its formation energy is -7.48 eV. Psi-BN exhibited strong ultraviolet activity, suggesting its potential as an efficient UV collector. Furthermore, we determined critical mechanical properties of Psi-BN, such as the elastic stiffness constants, Young's modulus (250-300 GPa), and Poisson ratio (0.7), providing valuable insights into its mechanical behavior.Comment: 13 pages, 7 figure

On Matrix Superpotential and Three-Component Normal Modes

We consider the supersymmetric quantum mechanics (SUSY QM) with three- component normal modes for the Bogomol'nyi-Prasad-Sommerfield (BPS) states. An explicit form of the SUSY QM matrix superpotential is presented and the corresponding three-component bosonic zero-mode eigenfunction is investigated.Comment: 17 pages, no figure. Paper accepted for publication in Journal of Physics A: Mathematical and Theoretica

Changing the production chain of Amazonian pirarucu.

This article summarizes these recent findings and envisions how these are impacting the production sector in the short and medium terms. Recent studies in Brazil have addressed the main challenges faced by commercial producers of pirarucu, including breeding, larval rearing, grow-out, feeding, health management, processing and more

What can Mott insulators teach us about density-functional theory (and vice versa)?

We study the Mott insulating phase of the one-dimensional Hubbard model using a local-density approximation (LDA) that is based on the Bethe Ansatz (BA). Unlike conventional functionals, the BA-LDA has an explicit derivative discontinuity. We demonstrate that as a consequence of this discontinuity the BA-LDA yields the correct Mott gap, independently of the strength of the correlations. A convenient analytical formula for the Mott gap in the thermodynamic limit is also derived. We find that in one-dimensional quantum systems the contribution of the discontinuity to the full gap is more important than that of the band-structure gap, and discuss some consequences this finding has for electronic-structure calculations.Comment: 4 pages 3 figures v2. (minor revisions) to appear in Europhysics Letter

Feeding rate and feeding frequency during the grow-out phase of tambaqui (Colossoma macropomum) in earthen ponds.

Adequate feeding protocols are extremely important for the technical and economic feasibility of fish production systems. Two feeding rates, 3% and 4% body weight per day (3%BW and 4%BW), and two feeding frequencies, twice and three times a day, were tested during 84 days at the initial grow-out phase of tambaqui (94.5 ± 6.4 g) in earthen ponds. No mortalities or difference in growth between treatments were observed during the trial. Total feed intake and feed conversion ratio were low in the fish fed at 3%BW. Fat deposition in the fish carcass and concentration of glycogen and lipid vacuoles in the hepatocytes were also low in fish fed at 3%BW. Plasma cholesterol and triglycerides were higher in the fish fed three times a day at 4%BW. Increased concentration of malonaldehyde was observed in the carcass of fish fed three times a day at 4%BW at the end of the storage period. Fish fed twice a day presented higher total feed intake per meal than fish fed three times a day, demonstrating that tambaqui was able to regulate the feed intake to benefit from a low feeding frequency. No difference was observed in pond phytoplankton and zooplankton concentration or sediment chemistry. Fish fed at 3%BW presented higher stomach content weight, demonstrating the contribution of the natural food as a complementary nutrition to tambaqui. Based on the results, tambaqui of 95–350 g reared in earthen ponds may be fed twice a day at 3%BW