Multiple scattering formalism for correlated systems: A KKR+DMFT approach

We present a charge and self-energy self-consistent computational scheme for correlated systems based on the Korringa-Kohn-Rostoker (KKR) multiple scattering theory with the many-body effects described by the means of dynamical mean field theory (DMFT). The corresponding local multi-orbital and energy dependent self-energy is included into the set of radial differential equations for the single-site wave functions. The KKR Green's function is written in terms of the multiple scattering path operator, the later one being evaluated using the single-site solution for the $t$-matrix that in turn is determined by the wave functions. An appealing feature of this approach is that it allows to consider local quantum and disorder fluctuations on the same footing. Within the Coherent Potential Approximation (CPA) the correlated atoms are placed into a combined effective medium determined by the dynamical mean field theory (DMFT) self-consistency condition. Results of corresponding calculations for pure Fe, Ni and Fe$_{x}$Ni$_{1-x}$ alloys are presented.Comment: 25 pages, 5 fig. acepted PR

UJI AKTIVITAS PENURUNAN KADAR ASAM URAT EKSTRAK ETANOL BUAH PARE (Momordica charantia L.) PADA TIKUS PUTIH JANTAN (Rattus norvegicus) YANG DIINDUKSI KAFEIN

ABSTRACTBitter melon fruit (Momordica charantia L.) is one of the plants that contains flavonoid compound supposedly as anti-hyperuricemic activity. This study aims to determine the potential activity of reducing uric acid levels from the ethanol extract of bitter melon fruit (Momordica charantia L.) on white wistar male rats (Rattus norvegicus) induced with caffeine. This study is a laboratory experiment using a complete randomized design. A total of 15 rats were divided into 5 groups : negative control (CMC 1%), positive control (Allopurinol), and treatment group of bitter melon fruit (Momordica charantia L.) extract 0,9 mg, 1,8 mg, and 3,6 mg. Hyperuricemic condition was induced by oral administration of  27 mg/200 gr caffeine for 6 days. The uric acid levels was measured before the rats was induced, 6 days after induced and every 3 days of 9 days of treatment. The data obtained were analyzed by ANOVA (Analisis of Variance) and LSD (Least Significant Different). The results show that the dose group of the ethanol extrack of bitter melon fruit had comparable with positive control of Allopurinol in decrease uric acid levels. The conclusion was the ethanol extract of bitter melon fruit (Momordica charantia L.) had anti-hyperuricemic activity in male white rats (Rattus norvegicus) dose 0,9 mg, 1,8 mg and 3,6 mg. Keywords  : Momordica charantia L., antihiperuricemia, Rattus norvegicus, caffeine.ABSTRAK Buah pare (Momordica charantia L.) adalah salah satu tanaman yang mengandung flavonoid yang diduga sebagai senyawa yang mempunyai aktivitas antihiperurisemia. Penelitian ini bertujuan untuk mengetahui potensi aktivitas penurunan kadar asam urat dari ekstrak etanol buah pare pada tikus putih jantan galur wistar (Rattus norvegicus). Jenis penelitian ini ialah eksperimen laboratorium menggunakan Rancangan Acak Lengkap. Sebanyak 15 ekor tikus dibagi dalam 5 kelompok perlakuan : kontrol negatif (CMC 1%), kontrol positif (Allopurinol), dan kelompok dosis uji yaitu pemberian ekstrak etanol buah pare 0,9 mg/200 gr BB; 1,8 mg/200 gr BB; 3,6 mg/200 gr BB. Induksi hiperurisemia dilakukan dengan kafein dosis 27 mg/200 gr selama 6 hari. Pengukuran kadar asam urat dilakukan sebelum induksi, 6 hari setelah diinduksi dan setiap 3 hari selama 9 hari perlakuan. Data yang diperoleh kemudian dianalisis secara statistik menggunakan ANOVA (Analysis of Variance) dan LSD (Least Significant Different). Hasil penelitian menunjukkan bahwa kelompok dosis ekstrak etanol buah pare memiliki aktivitas yang sebanding dengan kontrol positif allopurinol dalam menurunkan kadar asam urat. Kesimpulannya ekstrak etanol buah pare (Momordica charantia L.) memiliki aktivitas antihiperurisemia pada tikus putih jantan (Rattus norvegicus) pada dosis 0,9 mg/200 gr BB; 1,8 mg/200 gr BB; 3,6 mg/200 gr BB. Kata kunci : Momordica charantia L., antihiperurisemia, Rattus norvegicus, kafein

Calculating linear response functions for finite temperatures on the basis of the alloy analogy model

A scheme is presented that is based on the alloy analogy model and allows to account for thermal lattice vibrations as well as spin fluctuations when calculating response quantities in solids. Various models to deal with spin fluctuations are discussed concerning their impact on the resulting temperature dependent magnetic moment, longitudinal conductivity and Gilbert damping parameter. It is demonstrated that using the Monte Carlo (MC) spin configuration as an input, the alloy analogy model is capable to reproduce results of MC simulations on the average magnetic moment within all spin fluctuation models under discussion. On the other hand, response quantities are much more sensitive to the spin fluctuation model. Separate calculations accounting for either the thermal effect due to lattice vibrations or spin fluctuations show their comparable contributions to the electrical conductivity and Gilbert damping. However, comparison to results accounting for both thermal effects demonstrate violation of Matthiessen's rule, showing the non-additive effect of lattice vibrations and spin fluctuations. The results obtained for bcc Fe and fcc Ni are compared with the experimental data, showing rather good agreement for the temperature dependent electrical conductivity and Gilbert damping parameter

Magnetic anisotropy of deposited transition metal clusters

We present results of magnetic torque calculations using the fully relativistic spin-polarized Korringa-Kohn-Rostoker approach applied to small Co and Fe clusters deposited on the Pt(111) surface. From the magnetic torque one can derive amongst others the magnetic anisotropy energy (MAE). It was found that this approach is numerically much more stable and also computationally less demanding than using the magnetic force theorem that allows to calculate the MAE directly. Although structural relaxation effects were not included our results correspond reasonably well to recent experimental data

Continuous Bose-Einstein condensation

Bose-Einstein condensates (BECs) are macroscopic coherent matter waves that have revolutionized quantum science and atomic physics. They are essential to quantum simulation and sensing, for example underlying atom interferometers in space and ambitious tests of Einstein's equivalence principle. The key to dramatically increasing the bandwidth and precision of such matter-wave sensors lies in sustaining a coherent matter wave indefinitely. Here we demonstrate continuous Bose-Einstein condensation by creating a continuous-wave (CW) condensate of strontium atoms that lasts indefinitely. The coherent matter wave is sustained by amplification through Bose-stimulated gain of atoms from a thermal bath. By steadily replenishing this bath while achieving 1000x higher phase-space densities than previous works, we maintain the conditions for condensation. This advance overcomes a fundamental limitation of all atomic quantum gas experiments to date: the need to execute several cooling stages time-sequentially. Continuous matter-wave amplification will make possible CW atom lasers, atomic counterparts of CW optical lasers that have become ubiquitous in technology and society. The coherence of such atom lasers will no longer be fundamentally limited by the atom number in a BEC and can ultimately reach the standard quantum limit. Our development provides a new, hitherto missing piece of atom optics, enabling the construction of continuous coherent matter-wave devices. From infrasound gravitational wave detectors to optical clocks, the dramatic improvement in coherence, bandwidth and precision now within reach will be decisive in the creation of a new class of quantum sensors.Comment: 17 pages, 10 figure

Electronic structure of β\beta-SiAlON: effect of varying Al/O concentration at finite temperatures relevant for thermal quenchin

$\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ is a prominent example of systems suitable as hosts for creating materials for light-emitting diodes. In this work, the electronic structure of a series of ordered and disordered $\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ systems is investigated by means of ab initio calculations, using the FLAPW and the Green function KKR methods. Finite temperature effects are included within the alloy analogy model. We found that the trends with the Al/O doping are similar for ordered and disordered structures. The electronic band gap decreases with increasing $z$ by about 1 eV when going from $z$=0 to $z$=2. The optical gap decreases analogously as the electronic band gap. The changes in the density of states (DOS) at Si and N atoms introduced by doping $\beta$-Si$_{3}$N$_{4}$ with Al and O are comparable to the DOS at Al and O atoms themselves. The bottom of the conduction band in $\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ is formed by extended states residing on all atomic types. Increasing the temperature leads to a shift of the bottom of the conduction band to lower energies. The amount of this shift increases with increasing doping $z$.Comment: 11 pages, 11 figures, 1 tabl