Computer Physics Communications

Light antinuclei, like antideuteron and antihelium-3, are ideal probes for new, exotic physics because their astrophysical backgrounds are suppressed at low energies. In order to exploit fully the inherent discovery potential of light antinuclei, a reliable description of their production cross sections in cosmic ray interactions is crucial. We provide therefore the cross sections of antideuteron and antihelium-3 production in pp, pHe, Hep, HeHe, p¯p and p¯He collisions at energies relevant for secondary production in the Milky Way, in a tabulated form which is convinient to use. These predictions are based on QGSJET-II-04m and the state of the art coalescence model WiFunC, which evaluates the coalesence probability on an event-by-event basis, including both momentum correlations and the dependence on the emission volume. In addition, we comment on the importance of a Monte Carlo description of the antideuteron production and on the use of event generators in general. In particular, we discuss the effect of two-particle momentum correlations provided by Monte Carlo event generators on antinuclei production.

In this article, a new version of the Real-time Image Stream Algorithms (RISA) data processing suite is introduced. It now features online detector data acquisition, high-throughput data dumping and enhanced real-time data processing capabilities. The achieved low-latency real-time data processing extends the application of ultrafast electron beam X-ray computed tomography (UFXCT) scanners to real-time scanner control and process control. We implemented high performance data packet reception based on data plane development kit (DPDK) and high-throughput data storing using both hierarchical data format version 5 (HDF5) as well as the adaptable input/output system version 2 (ADIOS2). Furthermore, we extended RISA's underlying pipelining framework to support the fork-join paradigm. This allows for more complex workflows as it is necessary, e.g. for online data processing. Also, the pipeline configuration is moved from compile-time to runtime, i.e. processing stages and their interconnections can now be configured using a configuration file. In several benchmarks, RISA is profiled regarding data acquisition performance, data storage throughput and overall processing latency. We found that using direct IO mode significantly improves data writing performance on the local data storage. We could further prove that RISA is now capable of concurrently receiving, processing and storing data from up to 768 detector channels (3072 MB/s) at 8000 fps on a single-GPU computer in real-time.

We describe the new version 2.0.0 of the code DIRQFAM that calculates the multipole response of even-even axially symmetric deformed nuclei using the framework of relativistic self-consistent mean-field models. The response is calculated by implementing the finite amplitude method for relativistic quasiparticle random phase approximation. In the new version, we have implemented the following features: (i) meson-exchange interactions, (ii) low-rank method for calculating induced densities and currents, (iii) generalized minimal residual method (GMRES), (iv) evaluation of the nucleon localization function, (v) extraction of the QRPA transition matrix elements and eigenfrequencies, (vi) evaluation of the H^11 part of the induced Hamiltonian, (vii) multipole excitation operators up J <= 5 to are now included.

We introduce tqix.pis, a library of tqix, for quantum dynamics simulation of spin ensembles. The library emulates a dynamic process by a quantum circuit, including initializing a quantum state, executing quantum operators, and measuring the final state. It utilizes collective processes in spin ensembles to reduce the dimension from exponentially to quadratically with the number of particles, i.e., the quantum state spans in Dicke basis. It also facilitates the simulation time with multi-core processors and Graphics Processing Units. The library is thus applicable for the simulation of ensembles of large number of particles that have collective properties. Various phenomena, such as spin squeezing, variational quantum squeezing, quantum phase transition, and many-body quantum dynamics, can be simulated using the library.

A method is presented to include irregular domain boundaries in a geometric multigrid solver. Dirichlet boundary conditions can be imposed on an irregular boundary defined by a level set function. Our implementation employs quadtree/octree grids with adaptive refinement, a cell-centered discretization and pointwise smoothing. Boundary locations are determined at a subgrid resolution by performing line searches. For grid blocks near the interface, custom operator stencils are stored that take the interface into account. For grid block away from boundaries, a standard second-order accurate discretization is used. The convergence properties, robustness and computational cost of the method are illustrated with several test cases.

We report an implementation of the hadron-hadron ($pp$ and $p\bar{p}$) collision mode to the Monte Carlo event generator ReneSANCe~--- the code that was previously developed for $e^{+}e^{-}$ collisions. The described extension of ReneSANCe currently contains neutral and charged current Drell-Yan processes $pp[p\bar{p}] \to ZX \to \ell^+\ell^-X$, $pp[p\bar{p}] \to W^+X \to \ell^+\nu_\ell X$ and $pp[p\bar{p}] \to W^-X \to \ell^-\bar{\nu}_\ell X$. We take into account complete one-loop electroweak (EW) and one-loop QCD corrections to these processes. The calculation is based on the SANC (Support for Analytic and Numeric Calculations for experiments at colliders) modules. The generator is constructed in such a way that new processes can be easily added. The paper contains a theoretical description of the SANC approach, numerical validations and a manual.

The Bethe–Salpeter equation (BSE) approach becomes a methodology commonly used for simulating excitonic and optical properties in computer materials sciences. However, BSE approach based directly on first principles demands a high computational cost, being prohibitive for larger systems. In order to overcome this challenge, we have developed WanTiBEXOS, a parallel computational FORTRAN code, constituted of a maximally localized Wannier functions based tight-binding (MLWF-TB) model in conjunction with BSE framework. The MLWF-TB Hamiltonian used in WanTiBEXOS package can be obtained via any density functional theory package interfaced with Wannier90 code. It's expected, due MLWF-TB formalism, a computational time reduction around one or more orders of magnitude in comparison with BSE ab initio implementations. In order to demonstrate its reliability, flexibility, efficiency and versatility of WanTiBEXOS, we simulate electronic and optical property calculations for the representative materials, including conventional bulk semiconductors, perovskites, nano-monolayer materials and van der Waals heterostructures.

TBPLaS is an open-source software package for the accurate simulation of physical systems with arbitrary geometry and dimensionality utilizing the tight-binding (TB) theory. It has an intuitive object-oriented Python application interface (API) and Cython/Fortran extensions for the performance-critical parts, ensuring both flexibility and efficiency. Under the hood, numerical calculations are mainly performed by both exact diagonalization and the tight-binding propagation method (TBPM) without diagonalization. Especially, the TBPM is based on the numerical solution of the time-dependent Schrödinger equation, achieving linear scaling with system size in both memory and CPU costs. Consequently, TBPLaS provides a numerically cheap approach to calculate the electronic, optical, plasmon and transport properties of large tight-binding models with billions of atomic orbitals. Current capabilities of TBPLaS include the calculations of band structure, density of states, local density of states, quasi-eigenstates, optical conductivity, electrical conductivity, Hall conductivity, polarization function, dielectric function, plasmon dispersion, carrier mobility and velocity, localization length and free path, topological invariant, wave-packet propagation, etc. All the properties can be obtained with only a few lines of code. Other algorithms involving tight-binding Hamiltonians can be implemented easily due to the extensible and modular nature of the code. In this paper, we discuss the theoretical framework, implementation details and common workflow of TBPLaS, and give a few demonstrations of its applications.

Exploring the transport properties of different materials brings new avenue for basic understanding of emergent phenomena and practical applications in many different fields. Here, we report a program named as TRACK (TRAnsport properties for Correlated materials using Kubo formalism) which is written in Python 3 for calculating temperature dependent electrical conductivity, electronic part of thermal conductivity, Seebeck coefficient and Lorenz number. In this code, Kubo linear-response formalism is utilized for computing these parameters using both interacting and non-interacting electronic structure methods. The formula for transport coefficients is accordingly modified to obtain the transport parameters under relaxation time approximation using band-theory. The basic inputs of this program are the structural information, dense k-points sampling in the irreducible part of the Brillouin zone and the information of velocity matrix elements, which can be calculated using third-party ab-initio package. TRACK is expected to calculate the transport properties of different class of materials. The code has been benchmarked by performing calculation on three different types of materials namely Vanadium (V), FeSi and LaCoO3, which are metal, semiconductor and Mott insulator, respectively. The temperature dependent behaviour of the transport coefficients for these materials show fairly good agreement with the corresponding experimental data.

We present TChem, a performance portable software toolkit to enable the analysis of complex kinetic mechanisms. The software provides tools for gas-phase and surface chemistry, thermodynamic properties, and implements formulations for several canonical reactor models. Analytical derivatives necessary to construct Jacobian matrices corresponding to all implemented functionalities are available through automatic differentiation. TChem uses the Kokkos framework to achieve portability across multiple heterogeneous computing platforms with a single version of the code. We implement a hierarchical parallelism framework to enable efficient chemical source term and thermodynamic property evaluations over the number of samples assigned to the local computing device. We analyze parallel efficiency results extracted from test cases for thermodynamic properties, source terms, and Jacobians evaluations on Intel Xeon CPUs and NVIDIA Volta GPUs.