VESUVIO+: The Current Testbed for a Next-generation Epithermal Neutron Spectrometer

Krzystyniak, Matthew; Romanelli, Giovanni; Fábián, Margit; Gutmann, Matthias J.; Festa, G.; Arcidiacono, Laura; Gigg, M.; Drużbicki, Kacper; Senesi, R.; Fernandez-Alonso, Félix

doi:10.1088/1742-6596/1021/1/012026

Cited by 21 publications

(38 citation statements)

References 19 publications

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“…The VESUVIO spectrometer at the ISIS Pulsed Neutron and Muon source was used to carry out DINS experiments to measure the hydride anion momentum distribution in La 2 LiHO 3 on a 22.7 g powder sample at a series of temperatures from 30 to 500 K, representing the range where the onset of hydride dynamics was previously reported [1,16]. The data was corrected for sample-composition dependent gamma background and multiple scattering using newly developed routines implemented in the MantidPlot computational environment [17].…”

Section: Methodsmentioning

confidence: 99%

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride

et al. 2019

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Kobayashi et al (6279) (Science 2016, 351) reported recently the existence of pure Hconductivity in the oxyhydride La 2−x−y Sr x+y LiH 1−x+y O 3−y , while demonstrating its functionality through a prototype solid-state Ti/La 2 LiHO 3 /TiH 2 battery. In this study, we probe the atomistic motion of La 2 LiHO 3 obtained by the promising halide salt flux method, via a combination of deep inelastic neutron scattering (DINS) and ab initio lattice dynamics (LD) calculations verified by vibrational inelastic neutron spectroscopy (INS). We successfully describe the measured momentum distributions from DINS via our LD calculations, without observing any diffusion activation over the temperature range reported by Kobayashi et al. This observation is corroborated by model predictions from our LD study, which reveals that the hydride anions remain bound within a 3D-harmonic potential. We conclude that with the current synthesis parameters, the method produces a vacancy free lattice, and that a necessary ingredient for diffusive motion of His the presence of a large population of vacancies. Based on the harmonic prediction for the hydrogen kinetic energy, we derive a picture of the evolution of the effective bonding potential for the hydride anions, and link this to the dynamics associated with decomposition of the oxyhydride.

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Section: Methodsmentioning

confidence: 99%

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride

et al. 2019

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“…NCS experiments were performed at 180 and 240 K on the VESUVIO spectrometer, also located at the ISIS Facility [28][29][30][31]. The experimental and data-analysis protocol for VESUVIO measurements is explained in more detail elsewhere [28][29][30][31][32][33][34][35].…”

Section: Methodsmentioning

confidence: 99%

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

Drużbicki

Krzystyniak

Hollas

et al. 2018

J. Phys.: Conf. Ser.

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Abstract. With an increase of computational capabilities, ab initio molecular dynamics becomes the natural choice for exploring the nuclear dynamics of solids. As based on classical mechanics, the validity of this approach is, in-principle, limited to the high-T regime, whilst low-temperature simulations require inclusion of quantum effects. The methods commonly used to account for nuclear quantum effects are based on the path-integral formalism, which become, however, particularly time consuming when high accuracy methods are used for calculating forces. Recently, new efficient alternative approaches to account for quantum nature of nuclei have been proposed, using so-called quantum thermostats. In this work, we examine the simulations performed with the quantum colored-noise thermostat introduced by Ceriotti [Phys. Rev. Lett., 103:030603, 2009]. We present the tests of portable implementation of the quantum thermostat in the ABIN program, which has been extended to periodic systems through the interface to CASTEP, a leading spectroscopy-oriented plane-wave density functional theory code. The range of applicability of quantum-thermostatted molecular dynamics simulations for the interpretation of neutron scattering data was examined and compared to classical molecular dynamics and lattice-dynamics simulations, using solid formic acid case as a test bed. We find that the approach is particularly useful for the modeling of low-temperature inelastic neutron scattering spectra as well as provides some theoretical estimate for the low-limit of the mean kinetic energy. While finding the quantum-thermostat to seriously affect the dynamic properties of the title system, we illustrate to which extent the unperturbed response can be successfully recovered. IntroductionMolecular dynamics (MD) has evolved into a powerful numerical method to investigate structural and dynamical properties of condensed matter [1]. For an atom, these calculations are, however, only valid in the classical limit, i.e. for temperatures safely above the Debye temperature that signals the onset of quantum effects. The Debye temperature is often of the order of few hundred Kelvins and nuclear quantum effects (NQEs) are thus indeed important over a wide range of temperatures [2,3].Quantum fluctuations stemming from the Heisenberg uncertainty principle make the energy of a particle at 0 K higher than a the potential energy minimum, leading to a concept of zero point energy (ZPE) (see Fig. 1). While ZPE reflects the quantum nature of atomic motion, it can be approximately accounted for by lattice-dynamics calculations, which, by definition, are based on the quantum harmonic oscillator model.

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“…The effort of the community towards this end is well represented in the collection of articles presented here, as well as in Ref. [13]. For example, Nardini et al present an interesting combination of NRCA and other chemometric tools, in particular principal-component analysis, applied to archaeological artefacts so as to identify trace elements, and thereby their origin and history.…”

Section: Neutron-induced Photon Spectroscopiesmentioning

confidence: 97%

“…Furthermore, a number of recent investigations carried out on the VESUVIO spectrometer [7], the flagship instrument for eV neutron spectroscopy at the ISIS Facility [8], successfully combined DINS with concurrent Neutron Diffraction (ND) measurements [9,10], or employed broad-range Neutron Transmission (NT) [11,12]. Moreover, a novel trend of concurrent characterisation of condensed-matter systems by means of DINS, ND, and Neutron Resonance Capture Analysis (NRCA) is proving to be a potent strategy and thus is gaining momentum [13].…”

Section: Introductionmentioning

confidence: 99%

The road to a station for epithermal and thermal neutron analysis

Romanelli

Krzystyniak

Festa

et al. 2018

J. Phys.: Conf. Ser.

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Abstract.Despite the large variety of research interests and themes motivating the current neutron research included in this collection, we have found common denominators characterising the manner in which the chosen research methodology tries to tackle the envisaged scientific questions. This article attempts to characterise those trends in current research with the aim of identifying the main mid-to-long term opportunities faced by electron-Volt neutron spectroscopy. The main realisation from this exercise is that the scientific community seems eager to combine neutron-based techniques over a broad energy range. To this end, the most natural choice seems to be to resort to neutron instruments where such capabilities are already present from the outset, with the most prominent example being the VESUVIO spectrometer at the ISIS pulsed neutron and muon source in the UK. However broad the operational basis of the existing neutron beamline infrastructure may be, progress, achievable only through further instrument upgrades, is the only way forward. The need to move forward is clearly seen within the community and is well documented by the research presented in this collection. This need for a substantial upgrade has crystallised in the form of a proposition to build a station rather than a conventional beamline, for Epithermal and Thermal Neutron Analysis station, hereafter ETNA.

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VESUVIO+: The Current Testbed for a Next-generation Epithermal Neutron Spectrometer

Cited by 21 publications

References 19 publications

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

The road to a station for epithermal and thermal neutron analysis

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VESUVIO+: The Current Testbed for a Next-generation Epithermal Neutron Spectrometer

Cited by 21 publications

References 19 publications

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La2LiHO3 oxyhydride

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La2LiHO3 oxyhydride

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

The road to a station for epithermal and thermal neutron analysis

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Product

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A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride

A combined deep inelastic neutron scattering and ab initio lattice dynamics study of the hydride anion dynamics and bonding in La₂LiHO₃ oxyhydride