TRIQS/CTHYB: A Continuous-Time Quantum Monte Carlo Hybridization Expansion Solver for Quantum Impurity Problems

We present TRIQS/CTHYB, a state-of-the art open-source implementation of the continuous-time hybridisation expansion quantum impurity solver of the TRIQS package. This code is mainly designed to be used with the TRIQS library in order to solve the self-consistent quantum impurity problem in a multi-orbital dynamical mean field theory approach to strongly-correlated electrons, in particular in the context of realistic calculations. It is implemented in C++ for efficiency and is provided with a high-level Python interface. The code is ships with a new partitioning algorithm that divides the local Hilbert space without any user knowledge of the symmetries and quantum numbers of the Hamiltonian. Furthermore, we implement higher-order configuration moves and show that such moves are necessary to ensure ergodicity of the Monte Carlo in common Hamiltonians even without symmetry-breaking.Comment: 19 pages, this is a companion article to that describing the TRIQS librar

Improved wave functions for quantum Monte Carlo

Quantum Monte Carlo (QMC) methods can yield highly accurate energies for correlated quantum systems. QMC calculations based on many-body wave functions are considerably more accurate than density functional theory methods, and their accuracy rivals that of the most sophisticated quantum chemistry methods. This thesis is concerned with the development of improved wave function forms and their use in performing highly-accurate quantum Monte Carlo calculations. All-electron variational and diffusion Monte Carlo (VMC and DMC) calculations are performed for the first-row atoms and singly-positive ions. Over 98% of the correlation energy is retrieved at the VMC level and over 99% at the DMC level for all the atoms and ions. Their first ionization potentials are calculated within chemical accuracy. Scalar relativistic corrections to the energies, mass-polarization terms, and one- and two-electron expectation values are also evaluated. A form for the electron and intracule densities is presented and fits to this form are performed. Typical Jastrow factors used in quantum Monte Carlo calculations comprise electron-electron, electron-nucleus and electron-electron-nucleus terms. A general Jastrow factor capable of correlating an arbitrary of number of electrons and nuclei, and including anisotropy is outlined. Terms that depend on the relative orientation of electrons are also introduced and applied. This Jastrow factor is applied to electron gases, atoms and molecules and is found to give significant improvement at both VMC and DMC levels. Similar generalizations to backflow transformations will allow useful additional variational freedom in the wave function. In particular, the use of different backflow functions for different orbitals is expected to be important in systems where the orbitals are qualitatively different. The modifications to the code necessary to accommodate orbital-dependent backflow functions are described and some systems in which they are expected to be important are suggested

TRIQS: A Toolbox for Research on Interacting Quantum Systems

We present the TRIQS library, a Toolbox for Research on Interacting Quantum Systems. It is an open-source, computational physics library providing a framework for the quick development of applications in the field of many-body quantum physics, and in particular, strongly-correlated electronic systems. It supplies components to develop codes in a modern, concise and efficient way: e.g. Green's function containers, a generic Monte Carlo class, and simple interfaces to HDF5. TRIQS is a C++/Python library that can be used from either language. It is distributed under the GNU General Public License (GPLv3). State-of-the-art applications based on the library, such as modern quantum many-body solvers and interfaces between density-functional-theory codes and dynamical mean-field theory (DMFT) codes are distributed along with it.Comment: 27 page

Renormalization of effective interactions in a negative charge-transfer insulator

We compute from first principles the effective interaction parameters appropriate for a low-energy description of the rare-earth nickelate LuNiO$_{3}$ involving the partially occupied $e_g$ states only. The calculation uses the constrained random-phase approximation and reveals that the effective on-site Coulomb repulsion is strongly reduced by screening effects involving the oxygen-$p$ and nickel-$t_{2g}$ states. The long-range component of the effective low-energy interaction is also found to be sizeable. As a result, the effective on-site interaction between parallel-spin electrons is reduced down to a small negative value. This validates effective low-energy theories of these materials proposed earlier. Electronic structure methods combined with dynamical mean-field theory are used to construct and solve an appropriate low-energy model and explore its phase diagram as a function of the on-site repulsion and Hund's coupling. For the calculated values of these effective interactions we find, in agreement with experiments, that LuNiO$_{3}$ is a metal without disproportionation of the $e_g$ occupancy when considered in its orthorhombic structure, while the monoclinic phase is a disproportionated insulator.Comment: 10 pages, 4 figure

Evaluation of endometrium by transvaginal ultrasonography and hysteroscopy and its correlation with histopathology in perimenopausal women with abnormal uterine bleeding at tertiary rural centre

Background: Abnormal uterine bleeding is one of the commonest clinical presentation ac-counts for 33% gynaecological consultations and this proportion rises to 70% in perimenopausal and postmenopausal age group in any gynaecology clinic. The most probable etiology of abnormal uterine bleeding relates to the patients reproductive age. Various diagnostic techniques have been evolved over the periods to determine the etiology of abnormal uterine bleeding in perimenopausal women, but their accuracy has not been compared properly. The aim of study is to evaluate the endometrium by transvaginal ultrasonography and hysteroscopy and its correlation with histopathology in perimenopausal patients with abnormal uterine bleeding.Methods: Total 96 patients in perimenopausal age group, admitted with chief complaints of ab-normal uterine bleeding were included. All patients underwent transvaginal ultrasonography and hysteroscopy, followed by hysteroscopy guided biopsy and histopathological examination. Accuracy, sensitivity, specificity, positive predictive value and negative predictive value were calculated for both methods and compared, considering histopathological diagnosis as gold standard.Results: Mean age of patients was 44.05±3.29. Hysteroscopy has high accuracy, sensitivity, specificity, positive predictive value and negative predictive value than Transvaginal sonography for diagnosis of all endometrial and intrauterine pathologies.Conclusions: Hysteroscopy results are more consistent with the results of histopathology. Hysteroscopy and hysteroscopy guided biopsy has been proven as gold standard for endometrial evaluation of patients with abnormal uterine bleeding. TVS can be used as most cost effective first step investigation in cases of perimenopausal bleeding

Paget’s Disease of Maxilla: A Case Report

Paget disease of bone (PDB) is an idiopathic, chronic progressive disease of the bone, characterized by disordered pattern of bone resorption and formation. It has been observed to manifest itself as both monostotic and polyostotic disease. The scientific literature does not report a lot of cases on the incidence of this disease involving the jaws. In India, however a few cases have been reported in the recent times. Paget’s disease manifests itself as an asymptomatic disorder until it progresses onto the advanced stage where it becomes painful. Thus, its diagnosis on radiographs in the early stage is of paramount importance in order to deter its complications which may not only end up in disability but also can be fatal to life

TRIQS/DFTTools: A TRIQS application for ab initio calculations of correlated materials

We present the TRIQS/DFTTools package, an application based on the TRIQS library that connects this toolbox to realistic materials calculations based on density functional theory (DFT). In particular, TRIQS/DFTTools together with TRIQS allows an efficient implementation of DFT plus dynamical mean-field theory (DMFT) calculations. It supplies tools and methods to construct Wannier functions and to perform the DMFT self-consistency cycle in this basis set. Post-processing tools, such as band-structure plotting or the calculation of transport properties are also implemented. The package comes with a fully charge self-consistent interface to the Wien2k band structure code, as well as a generic interface that allows to use TRIQS/DFTTools together with a large variety of DFT codes. It is distributed under the GNU General Public License (GPLv3).Comment: 18 pages, 6 figures, Comp. Phys. Comm. accepted versio

All-epitaxial, laterally structured plasmonic materials

Optoelectronic devices in the mid-infrared have attracted significant interest due to numerous potential applications in communications and sensing. Molecular beam epitaxial (MBE) growth of highly doped InAs has emerged as a promising “designer metal” platform for the plas- monic enhancement of mid-infrared devices. However, while typical plasmonic materials can be patterned to engineer strong localized reso- nances, the lack of lateral control in conventional MBE growth makes it challenging to create similar structures compatible with monolithically grown plasmonic InAs. To this end, we report the growth of highly doped InAs plasmonic ridges for the localized resonant enhancement of mid-IR emitters and absorbers. Furthermore, we demonstrate a method for regaining a planar surface above plasmonic cor- rugations, creating a pathway to epitaxially integrate these structures into active devices that leverage conventional growth and fabrication techniques.This research was partially supported by the National Science Foundation through the Center for Dynamics and Control of Materials: an NSF Materials Research Science and Engineering Center (MRSEC) under Cooperative Agreement No. DMR-1720595, as well as Nos. DMR-1839175 and ECCS-1926187. This work was performed in part at the University of Texas Microelectronics Research Center, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which was supported by the National Science Foundation (Grant No. ECCS-1542159).Center for Dynamics and Control of Material

SHOX Variations in Idiopathic Short Stature in North India and a Review of Cases from Asian Countries

INTRODUCTION: Short stature homeobox (SHOX) haploinsufficiency underlies idiopathic short stature (ISS) and Leri-Weill dyschondrosteosis. The worldwide prevalence of SHOX variations in ISS varies from 2.5% to 15.0%. The aim of this study was to assess the implication of SHOX variation in ISS in North Indians and compare this with other cases of SHOX variations from Asian population. METHODS: SHOX gene analysis was carried out by multiplex ligation-dependent probe amplification followed by Sanger sequencing in 54 patients with variable phenotypes. Comparison with other reports in a meta-analysis comprising the current study and 11 previous studies (n=979) was performed. RESULTS: SHOX analysis resulted in 12.9% positivity (7.4% deletions and 5.5% duplications). SHOX association was seen significantly related to gender, with predominance in females (p=0.047). Short arms and forearms were the only significantly associated trait seen in 51.9% of children. The overall prevalence of SHOX variation was 15.2% in Asians with ISS. No significant difference was found in geographical region-specific analysis. DISCUSSION AND CONCLUSION: This study summarises findings from the last decade and provides an updated picture of the prevalence of SHOX variations in Asians, emphasizing their potential as therapeutic targets in ISS patients. Further high quality, large investigations including functional validation is warranted to validate this association