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RHEED_DIFF_2D is an open-source software capable of performing qualitative numerical simulations of changes to the intensity of RHEED oscillations in the function of the layer deposited, employing various models of scattering crystal potential for heteroepitaxial structures of bcc (001) films nucleated on a fcc (001) surface, including the possible existence of various diffuse scattering models through the layer parallel to the surface. This model can be used for interpreting data weakly dependent on the azimuth of the incident electron beam direction and for 2D monolayer-by-monolayer growth modes. The program does not use any external data sources. Program title: RHEED_DIFF_2D CPC Library link to program files: https://doi.org/10.17632/83ht2kc8xt.1 Licensing provisions: GNU General Public License 3 Programming language used: C++ Journal reference of previous version: Computer Physics Communications 185 (2014) 3001–3009 Does the new version supersede the previous version?: No. It is a supplement to the previous version. [ABSTRACT FROM AUTHOR]

This paper introduces Eilmer, a general-purpose open-source compressible flow solver developed at the University of Queensland, designed to support research calculations in hypersonics and high-speed aerothermodynamics. Eilmer has a broad userbase in several university research groups and a wide range of capabilities, which are documented on the project's website, in the accompanying reference manuals, and in an extensive catalogue of example simulations. The first part of this paper describes the formulation of the code: the equations, physical models, and numerical methods that are used in a basic fluid dynamics simulation, as well as a handful of optional multi-physics models that are commonly added on to do calculations of hypersonic flow. The second section describes the processes used to develop and maintain the code, documenting our adherence to good programming practice and endorsing certain techniques that seem to be particularly helpful for scientific codes. The final section describes a half-dozen example simulations that span the range of Eilmer's capabilities, each consisting of some sample results and a short explanation of the problem being solved, which together will hopefully assist new users in beginning to use Eilmer in their own research projects. Program Title: Eilmer CPC Library link to program files: https://doi.org/10.17632/gy2ds2fyxm.1 Developer's repository link: https://github.com/gdtk-uq/gdtk Code Ocean capsule: https://codeocean.com/capsule/7226427 Licensing provisions: GPLv3 Programming language: D, Lua Supplementary material: https://gdtk.uqcloud.net Nature of problem: Eilmer solves the compressible Navier-Stokes equations with a particular emphasis on flows at hypersonic speeds. The code includes modelling for high-temperature gas effects such as chemical and vibrational nonequilibrium. Eilmer can be used for the simulation for unsteady and steady flows. Solution method: The code is implemented in D [1] and built on a finite-volume formulation that is capable of solving the Navier-Stokes equations in 2D and 3D computational domains, discretised with structured or unstructured grids. Grids may be generated using a built-in parametric scripting tool or imported from commercial gridding software. The inviscid fluxes are computed using the reconstruction-evolution approach. In structured-grid mode, reconstruction stencils up to fourth-order spatial accuracy are available. In unstructured-grid mode, least-squares reconstruction provides second-order spatial accuracy. A variety of flux calculators are available in the code. Viscous fluxes are computed with compact stencils with second-order spatial accuracy. For unsteady flows, explicit time-stepping with low-order RK-family schemes are available, along with a point-implicit Backward-Euler update scheme for stiff systems of equations. For steady flows, convergence can be greatly accelerated using a Jacobian-free Newton-Krylov update scheme, which seeks a global minimum in the residuals using a series of large pseudo-timesteps. Domain decomposition is used for parallel execution using both shared memory and distributed memory programming techniques. Additional comments including restrictions and unusual features: Eilmer provides a programmable interface for pre-processing, post-processing and user run-time customisations. The programmable interface is enabled using a built-in embedded interpreter for the Lua programming language [2]. Run-time customisations include used-defined boundary conditions, source terms and grid motion. [1] D Programming Language web page: https://dlang.org/. [2] Lua Programming Language web page: https://www.lua.org/. [ABSTRACT FROM AUTHOR]

In atomic structure and collision theory, the efficient spin-angular integration is known to be crucial and often decides, how accurate the properties and behavior of atoms can be predicted numerically. Various methods have been developed in the past to keep the computation (and implementation) of the spin-angular integration feasible for complex shell structures, including open d - and f -shell elements. To support such computations, we here provide a new implementation of the angular coefficients for jj -coupled and symmetry-adapted configuration states that is entirely built upon the quasi-spin formalism. The module SpinAngular is based on Julia, a new programming language for scientific computing, and supports a simple access to all (completely) reduced tensors, coefficients of fractional parentage for subshells with j ≤ 9 / 2 as well as the re-coupling coefficients from this formalism. Moreover, this module has been worked out for multiple purposes, including 1) the accurate calculation of atomic properties, 2) further studies on spin-angular integration theory, 3) the development of new or existing computer programs as well as 4) the manipulation of reduced matrix elements from this theory. The present implementation will therefore help advance the algebraic evaluation of many-electron (transition) amplitudes and to apply the theory to newly emerging research areas. Program title: SpinAngular CPC Library link to program files: https://doi.org/10.17632/jjpff3pysn.1 Code Ocean capsule: https://doi.org/10.24433/CO.3772334.v1 Licensing provisions: MIT License Programming language: Julia Nature of problem: For symmetric one- and two-particle operators, the (many-electron) matrix elements between symmetry-adapted configuration states can always be written as a sum of angular coefficient x interaction strength. While the interaction strengths describe the physical interaction and just depends on the (one-electron) orbitals of the active shells, the angular coefficients arise from the (many-electron) spin-angular integrals and are determined geometrically by the occupation and coupling of all electrons. These angular coefficients need to be calculated efficiently and often require special care. Solution method: The spin-angular approach [1] is implemented for (tensorial coupled) one-particle operators of arbitrary rank, scalar two-particle operators as well as for the manipulation of reduced matrix elements from this theory. [1] G. Gaigalas, Z. Rudzikas, C. Froese Fischer, J. Phys. B, At. Mol. Opt. Phys. 30 (1997) 3747. [ABSTRACT FROM AUTHOR]

This paper presents a version of simulation program, which facilitates the calculation of changes to the intensity of RHEED oscillations in the function of the glancing angle of incidence of the electron beam, employing various models of scattering crystal potential for heteroepitaxial structure of hexagonal (0001) GaN film nucleated on a 3C-SiC surface, including the possible existence of various diffuse scattering models through the layer parallel to the surface. New version program summary Title of program: RHEED_DIFF_Z Program Files doi: http://dx.doi.org/10.17632/52nxmwzkxx.1 Licensing provisions: GNU General Public License 3 Programming language used: C++ Journal reference of previous version: Computer Physics Communications 207 (2016) 536–538 Does the new version supersede the previous version?: No. It is a supplement to the previous version. Reasons for new version: Responding to users’ feedback we present a practical procedure of construction of simulation program, which facilitates the calculation of changes to the intensity of RHEED rocking curves, employing various models of scattering crystal potential for heteroepitaxial structure of hexagonal (0001) GaN film nucleated on a 3C-SiC(111) surface. Nature of problem: Growth of GaN layers on SiC is of importance for potential electronic device applications. Silicon carbide crystallizes in numerous different modifications, so-called polytypes [1]. Among them, only hexagonal structure 4H-SiC and 6H-SiC have been thoroughly investigated while the cubic 3C-SiC polytype is lagging behind in technological developments. The 3C-SiC has a Zincblende crystal structure and is characterized by an identical orientation of all bilayers in the crystal, where the atomic geometry is repeated every three bilayers along the c-axis this crystal structure ( Fig. 1 ). For this reason, 3C-SiC has the high electron mobility and saturation velocity by reducing phonon scattering resulting from the high symmetry. The lattice mismatch between GaN(0001) and 3C-SiC(111) is about 3.3%, and is smaller than the mismatch between GaN(0001) and Si(111) [2]. Therefore progress in investigations on crystal growth of GaN on 3C-SiC is a key issue for device developments related to this heterostructure. Researchers and technologists manufacturing two-dimensional heterostructures frequently use RHEED rocking curves to control growth of samples at the atomistic level of accuracy. The fundamental scientific problem in such research is to specify both interface type and growth mechanism for subsequent layers. Method of solution: RHEED intensities are calculated within the general framework described in Refs. [2] and [3]. Summary of revisions: The presented version of the program implements an original algorithm of self-consistent calculations for scattering potentials GaN(0001)/3C-SiC(111) and solving a time-independent Schrödinger equation for high-energy electrons. During the numerical calculations of the changes in the intensity of the specular beam in the function of the glancing angle, it was assumed that the azimuth of the incident beam direction corresponds to the one-beam condition, the electron energy equals 10 keV, the glancing angle was increased from 0 . 5 ∘ to 6 . 5 ∘ , and the value of α parameter = 0 . 1 and β = 0 . 5 for the MODEL3 of the scattering potential [3] with the model of ideal SiC/GaN interface [4]. References [1] G. R. Fisher and P. Barnes, Phil. Mag. B 61(2) (1990) 217-236. [2] A. Daniluk, Comput. Phys. Commun. 207 (2016) 536-538. [3] A. Daniluk, Comput. Phys. Commun. 185 (2014) 3001-3009. [4] H. Morkoç, Handbook of Nitride Semiconductors and Devices, Vol. 1: Materials Properties, Physics and Growth, Wiley VCH 2008. [ABSTRACT FROM AUTHOR]