Exact diagonalization solver for the extended dynamical mean-field theory

We present an efficient exact diagonalization scheme for the extended dynamical mean-field theory and apply it to the extended Hubbard model on the square lattice with nonlocal charge-charge interactions. Our solver reproduces the phase diagram of this approximation with good accuracy. Details on the numerical treatment of the large Hilbert space of the auxiliary Holstein-Anderson impurity problem are provided. Benchmarks with a numerically exact strong-coupling continuous-time quantum-Monte Carlo solver show better convergence behavior of the exact diagonalization in the deep insulator. Special attention is given to possible effects due to the discretization of the bosonic bath. We discuss the quality of real axis spectra and address the question of screening in the Mott insulator within extended dynamical mean-field theory.Comment: 12 pages, 8 figure

The redox transformations and nucleophilic replacements as possible metabolic reactions of the drug “Triazaverin”. The chemical modeling of the metabolic processes

As a model of metabolic transformations of antiviral drug “Triazaverin” and its analogues‑2-alkylthio‑6-nitro‑1,2,4-triazolo[5,1-c][1,2,4]triazine‑7-ones 1a-d examined the oxidation of alkylthio groups to the corresponding sulfoxides 2a-d and sulfones 3a-d, as well as the process of nucleophilic substitution sulfonyloxy group of cysteine and cysteamine with the formation of compounds 5 and 6

Role of direct exchange and Dzyaloshinskii-Moriya interactions in magnetic properties of graphene derivatives: C2_2F and C2_2H

According to the Lieb's theorem the ferromagnetic interaction in graphene-based materials with bipartite lattice is a result of disbalance between the number of sites available for $p_z$ electrons in different sublattices. Here, we report on another mechanism of the ferromagnetism in functionalized graphene that is the direct exchange interaction between spin orbitals. By the example of the single-side semihydrogenated (C$_2$H) and semifluorinated (C$_2$F) graphene we show that such a coupling can partially or even fully compensate antiferromagnetic character of indirect exchange interactions reported earlier [Phys. Rev. B {\bf 88}, 081405(R) (2013)]. As a result, C$_2$H is found to be a two-dimensional material with the isotropic ferromagnetic interaction and negligibly small magnetic anisotropy, which prevents the formation of the long-range magnetic order at finite temperature in accordance with the Mermin-Wagner theorem. This gives a rare example of a system where direct exchange interactions play a crucial role in determining a magnetic structure. In turn, C$_2$F is found to be at the threshold of the antiferromagnetic-ferromagnetic instability, which in combination with the Dzyaloshinskii-Moriya interaction can lead to a skyrmion state.Comment: 10 page

Ultrasound investigation in pregnant women with diabetes mellitus

Introduction. Ultrasound (US) has been used in obstetrics for more than 30 years and is considered to be reliable, simple, quick in results, painless and cheap method. The aim: to optimize the use of US in childbirth in pregnant women with diabetes and determine the outcome of childbirth, taking into account the condition of the fetus and newborn. Materials and methods. 52 pregnant women, among them 32 with diabetes mellitus (pre-gestational diabetes was in 20 persons and 12 persons had gestational diabetes) have been examined.  The average age of pregnant women in the main group was 29.8 ± 5.4 years, in the control group - 25.7 ± 4.3 years. All women in the main and control groups were primiparous. The gestation period in the main group was 39.1 ± 0.5 weeks [38.0; 39.6], in the control group - 39.5 ± 0.7 [38.4; 40.5] weeks. Clinical-laboratory and instrumental examinations were made. Control group consisted of  20 physiologically pregnant women. To determine the condition and size of the fetus and its progress in labor, immediately at the end of the first and during the second staage of labor, transabdominal and transperineal US and Doppler examination were performed with device HD 11 XE Phillips (USA). Results. Pregnant women with diabetes are more likely to have a pathological second stage of labors due to macrosomia and problems with the birth of the fetus, as evidenced by the lack of increased angle of progress and decreased head-perineal distance. The data obtained indicate the prospects of using ultrasound in childbirth as an objective non-invasive method for predicting the likelihood of vaginal birth, which will reduce operative delivery and perinatal pathology. Conclusions. The use of ultrasound in childbirth in women with diabetes and diabetic fetopathy can determine the possibility of complications in the promotion of the fetus, including clinical narrow pelvis, shoulder dystocia, the occurrence of distress, as evidenced by the Apgar scale and CLS. Intraparietal ultrasound helps to guide the plan of childbirth, reduce the frequency of cesarean delivery, perinatal morbidity and mortality, and birth trauma

Role of Coulomb correlation on magnetic and transport properties of doped manganites: La0.5Sr0.5MnO3 and LaSr2Mn2O7

Results of LSDA and LSDA+U calculations of the electronic structure and magnetic configurations of the 50% hole-doped pseudocubic perovskite La0.5Sr0.5MnO3 and double layered LaSr2Mn2O7 are presented. We demonstrate that the on-site Coulomb correlation (U) of Mn d electrons has a very different influence on the (i) band formations, (ii) magnetic ground states, (iii) interlayer exchange interactions, and (iv) anisotropy of the electrical transport in these two manganites. A possible reason why the LSDA failures in predicting observed magnetic and transport properties of the double layered compound - in contrast to the doped perovskite manganite - is considered on the basis of a p-d hybridization analysis.Comment: 11 pages, 3 figure

Cyclotron enhancement of tunneling

A state of an electron in a quantum wire or a thin film becomes metastable, when a static electric field is applied perpendicular to the wire direction or the film surface. The state decays via tunneling through the created potential barrier. An additionally applied magnetic field, perpendicular to the electric field, can increase the tunneling decay rate for many orders of magnitude. This happens, when the state in the wire or the film has a velocity perpendicular to the magnetic field. According to the cyclotron effect, the velocity rotates under the barrier and becomes more aligned with the direction of tunneling. This mechanism can be called cyclotron enhancement of tunneling