A parallel algorithm for Hamiltonian matrix construction in electron-molecule collision calculations: MPI-SCATCI

Construction and diagonalization of the Hamiltonian matrix is the rate-limiting step in most low-energy electron -- molecule collision calculations. Tennyson (J Phys B, 29 (1996) 1817) implemented a novel algorithm for Hamiltonian construction which took advantage of the structure of the wavefunction in such calculations. This algorithm is re-engineered to make use of modern computer architectures and the use of appropriate diagonalizers is considered. Test calculations demonstrate that significant speed-ups can be gained using multiple CPUs. This opens the way to calculations which consider higher collision energies, larger molecules and / or more target states. The methodology, which is implemented as part of the UK molecular R-matrix codes (UKRMol and UKRMol+) can also be used for studies of bound molecular Rydberg states, photoionisation and positron-molecule collisions.Comment: Write up of a computer program MPI-SCATCI Computer Physics Communications, in pres

ExoCross: a general program for generating spectra from molecular line lists

ExoCross is a Fortran code for generating spectra (emission, absorption) and thermodynamic properties (partition function, specific heat etc.) from molecular line lists. Input is taken in several formats, including ExoMol and HITRAN formats. ExoCross is efficiently parallelized showing also a high degree of vectorization. It can work with several line profiles such as Doppler, Lorentzian and Voigt and support several broadening schemes. Voigt profiles are handled by several methods allowing fast and accurate simulations. Two of these methods are new. ExoCross is also capable of working with the recently proposed method of super-lines. It supports calculations of lifetimes, cooling functions, specific heats and other properties. ExoCross can be used to convert between different formats, such as HITRAN, ExoMol and Phoenix. It is capable of simulating non-LTE spectra using a simple two-temperature approach. Different electronic, vibronic or vibrational bands can be simulated separately using an efficient filtering scheme based on the quantum numbers

High-Torque-Density Low-Cost Magnetic Gear Utilizing Hybrid Magnets and Advanced Materials

Two major challenges of existing high-performance magnetic gears are: (i) High content of rare-earth permanent magnets which results in high cost as well as price fluctuation; (ii) Conflict between mechanical and electromagnetic performances, especially in the design of highspeed rotor. A magnetic gear using a blend of magnet types, i.e NdFeB, or Dy-free NdFeB and ferrites, is proposed in this paper. The goal is to bring down the cost while retaining comparable torque-transducing performance to a baseline magnetic gear only using rare-earth NdFeB magnets. A variety of topologies based on different combinations of magnet types and geometric shapes have been studied and compared. In addition, the potential impact of using an advanced dual-phase material is evaluated. The goal is to eliminate the well-known tradeoff between rotor mechanical integrity and PM flux leakage

TauREx3 PhaseCurve: A 1.5D Model for Phase-curve Description

In recent years, retrieval analysis of exoplanet atmospheres have been very successful, providing deep insights on the composition and the temperature structure of these worlds via transit and eclipse methods. Analysis of spectral phase-curve observations, which in theory provide even more information, are still limited to a few planets. In the next decade, new facilities such as NASA–James Webb Space Telescope and ESA-Ariel will revolutionize the field of exoplanet atmospheres and we expect that a significant time will be spent on spectral phase-curve observations. Most current models are still limited in their analysis of phase-curve data as they do not consider the planet atmosphere as a whole or they require large computational resources. In this paper we present a semi-analytical model that will allow computing exoplanet emission spectra at different phase angles. Our model provides a way to simulate a large number of observations while being only about four times slower than the traditional forward model for plane–parallel primary eclipse. This model, which is based on the newly developed TauREx 3 framework, will be further developed to allow for phase-curve atmospheric retrievals

Local Jordanian Materials to Produce a Bakelite-base Construction Composite Material

In this investigation, a combined experimental approach of micro-structural observation and compressive load capacity testing were followed to determine the behavior of bakelite matrix material reinforced with Jordanian silica sand. It was found that the reinforced samples gave a higher maximum load capacity than the pure matrix, because the homogeneous structure helped in distributing the applied load between the matrix and the reinforcement. Moreover, the higher the volume fraction of the reinforcement, the higher the maximum load capacity of the composite. The maximum load capacity of the samples with 75% content of Jordanian silica sand was less than that of pure bakelite. On the other hand, the higher the particle size of the reinforcement, the higher the maximum load capacity of the composite. Composites of bakelite matrix gave a higher maximum load capacity than that of polystyrene matrix. In addition, a longitudinal brittle fracture was observed for the composites

Efficient Production of Hot Molecular Line Lists

Molecular line lists are of utmost importance in understanding and characterising the molecular composition of atmospheres from their spectra. Cool stars and exoplanets such as Hot Jupiters have temperature ranges that allow for a significant composition of molecules in their atmospheres with extremely complex and rich spectral structures. Building a comprehensive line-list to model such phenomena is a non-trivial task. Therefore efficient production is a necessity. This thesis presents three molecular line lists produced using the theoretical methodologies of the TROVE program suite. GPU Accelerated Intensities (GAIN) is a new addition to TROVE and allows for the rapid calculation of billions of transitions by exploiting graphics processing units (GPUs) to speed up the evaluation of the line strength by almost 1000x compared to previous codes. The program’s extensive usage in computing the 17 billion transitions for the hot phosphine line list SAlTY is briefly discussed. A hot H2CO line-list applicable to 1500 K is computed using TROVE and GAIN from a refined potential energy surface (PES) and ab initio dipole moment surface (DMS). Results are compared to experimental data and problems encountered from the PES refinement are discussed. A preliminary room temperature line list for H2O2 is produced from a purely ab initio PES and DMS and compared to experimental result. The ab initio PES is then refined to spectroscopic accuracy and a final hot line list is produced applicable up to 1250 K

ExoMol molecular line lists - XVII The rotation-vibration spectrum of hot SO3_3

Sulphur trioxide (SO$_3$) is a trace species in the atmospheres of the Earth and Venus, as well as well as being an industrial product and an environmental pollutant. A variational line list for $^{32}$S$^{16}$O$_{3}$, named UYT2, is presented containing 21 billion vibration-rotation transitions. UYT2 can be used to model infrared spectra of SO$_3$ at wavelengths longwards of 2 $\mu$m ($\nu < 5000$ cm$^{-1}$) for temperatures up to 800 K. Infrared absorption cross sections are also recorded at 300 and 500 C are used to validate the UYT2 line list. The intensities in UYT2 are scaled to match the measured cross sections. The line list is made available in electronic form as supplementary data to this article and at \url{www.exomol.com}.Comment: 15 pages, 10 figures, 9 tables MNRAS submitte

TauREx 3: A Fast, Dynamic, and Extendable Framework for Retrievals

TauREx 3 is the next generation of the TauREx exoplanet atmospheric retrieval framework for Windows, Mac and Linux. It is a complete rewrite with a full Python stack that makes it simple to use, high performance and dynamic/flexible. The new main taurex program is extremely modular, allowing the user to augment taurex functionalities with their own code and easily perform retrievals on their own parameters. This is achieved by dynamic determination of fitting parameters where TauREx 3 can detect new parameters for retrieval from the user code though a simple interface. TauREx 3 can act as a library with a simple 'import taurex' providing a rich set of classes and functions related to atmospheric modelling. A 10x speed-up in forward model computations is achieved compared to the previous version with a six-fold reduction in retrieval times whilst maintaining robust results. TauREx 3 intends to act as a standalone, all in one package for retrievals whilst the TauREx 3 python library can be used by the user to easily build or augment their own data pipelines

FRECKLL: Full and Reduced Exoplanet Chemical Kinetics distiLLed

We introduce a new chemical kinetic code FRECKLL (Full and Reduced Exoplanet Chemical Kinetics distiLLed) to evolve large chemical networks efficiently. FRECKLL employs `distillation' in computing the reaction rates, which minimizes the error bounds to the minimum allowed by double precision values ($\epsilon \leq 10^{-15}$). FRECKLL requires less than 5 minutes to evolve the full Venot2020 network in a 130 layers atmosphere and 30 seconds to evolve the Venot2020 reduced scheme. Packaged with FRECKLL is a TauREx 3.1 plugin for usage in forward modelling and retrievals. We present TauREx retrievals performed on a simulated HD189733 JWST spectra using the full and reduced Venot2020 chemical networks and demonstrate the viability of total disequilibrium chemistry retrievals and the ability for JWST to detect disequilibrium processes.Comment: 13 pages, 8 figure