<i>Ab initio</i>strategy for muon site assignment in wide band gap fluorides

Bernardini, Fabio; Bonfà, Pietro; Massidda, S.; Renzi, R. De

doi:10.1103/physrevb.87.115148

Cited by 64 publications

(82 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the solution of the Schrodinger equation we obtain a ground state energy E 0 = 0.6 eV (independently of the interpolation method and the boundary conditions used). The probability density of the ground state wave function (not shown) is well localized and, by considering the concept of turning point volume, 6 the same conclusion can be drawn from Figure 2a, where even the isosurface for V μ = 0.8 eV is found to be confined inside the points cloud acquired during the simulation.…”

Section: Articlesupporting

confidence: 73%

Efficient and Reliable Strategy for Identifying Muon Sites Based on the Double Adiabatic Approximation

Bonfà¹,

Sartori²,

Renzi³

2015

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

We revise the simple and yet powerful approach of the Double Adiabatic Approximation (DAA) to study positive muon embedding sites in condensed matter. This method introduces a tractable and reasonably accurate description of the quantum nature of the muon in Density Functional Theory (DFT) simulations aiming at identifying muon sites. Moreover, this approach overcomes the limitations of the harmonic approximation in terms of both computational efforts and accuracy. Notably, it also improves treatment of muon diffusion. We use the DAA and Nudged Elastic Band calculations to determine the muon sites and the activation energies between equivalent sites in MnSi and copper. In metallic Cu, the proposed phonon-assisted mechanism for the low-temperature muon diffusion in the lattice is confirmed. ■ INTRODUCTIONMuon spin rotation and relaxation (μSR) spectroscopy is an experimental technique that provides the time evolution of the muon spin polarization by exploiting the anisotropic emission of the decay positron.The main field of application of μSR is material science, but it is also adopted in chemistry for studying molecular dynamics and radical kinetics. 1−3 Both μ − SR and μ + SR exist, but, since μ − undergoes nuclear capture and the surviving μ − fall into atomic orbitals extremely close to the nuclei, μ + SR is more commonly used to investigate condensed matter.μSR experiments provide a measure of the microscopic field distribution at the interstitial site(s) where the μ + stop inside the sample. A seemingly embarrassing point is that these sites are usually unknown to the experimenter and the additional lack of knowledge on the perturbation generated locally by the positive muon probably represent the most common criticisms of the experimental technique. Even though in a large variety of cases ignoring the muon position does not represent a limitation, having access to information on interstitial sites and on muon-induced perturbations might be crucial to evaluate electronic properties such as long-range magnetic orders or localized magnetic moments.Predicting the position of interstitial muon sites is not a trivial task. During the final stages of thermalization in the sample the scattering between the muon and the atoms of the compound leads to a kinetic energy degradation from hundreds to tenths of electronvolts. Nonetheless, the identification of diamagnetic muon sites with approaches based on the Density Functional Theory (DFT) is emerging as a new and valuable strategy to routinely assist μSR experiments interpretation. After the pioneering work of Van de Walle et al., in recent years, this method, which provides information on the electronic and crystalline perturbations introduced by the muon, has been validated in many experimental cases with great success. 4−13 There are two main difficulties in the DFT approach. One is inherited from the mean-field description which cannot always correctly describe some classes of materials, like strongly correlated electrons systems or even some semiconductors mist...

show abstract

Section: Articlesupporting

confidence: 73%

Efficient and Reliable Strategy for Identifying Muon Sites Based on the Double Adiabatic Approximation

Bonfà¹,

Sartori²,

Renzi³

2015

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

show abstract

“…In contrast to a proton, this is not a trivial task for a μ + because it is a light particle and cannot be treated as a clamped point charge within the Born–Oppenheimer (BO) paradigm. Various ‐ quantum chemical procedures have been developed specially for muonic molecules to deduce their structures . Probably, the most theoretically (but not computationally) straightforward procedure is treating μ + s like electron as a quantum wave from the outset of the non‐adiabatic quantum chemical calculations by introducing its kinetic energy operator directly into the time‐independent Schrödinger equation .…”

Section: Resultsmentioning

confidence: 99%

Muon‐Substituted Malonaldehyde: Transforming a Transition State into a Stable Structure by Isotope Substitution

Goli

Shahbazian

2016

Chemistry A European J

View full text Add to dashboard Cite

Isotopes ubstitutionsa re usually conceived to play am arginal role on the structure and bondingp attern of molecules. However,arecent study [Angew.C hem. Int. Ed. 2014, 53,1 3706-13709; Angew.C hem. 2014, 126,1 3925-13929]f urther demonstrates that upon replacing ap roton with ap ositively charged muon, as the lightest radioisotope of hydrogen, radical changes in the nature of the structure and bonding of certains peciesm ay take place. The present report is ap rimary attemptt oi ntroduce another example of structural transformation on the basis of the malonaldehyde system.A ccordingly,u pon replacing the protonb etween the two oxygen atoms of malonaldehydew ith the positively charged muon as erious structuralt ransformationi so bserved. By using the ab initio nuclear-electronic orbitaln onBorn-Oppenheimer procedure, the nuclear configuration of the muon-substituted speciesi sd erived. The resulting nuclear configuration is much more similart ot he transition state of the proton transferi nm alonaldehyde rather than to the stable configuration of malonaldehyde. The comparison of the "atoms in molecules" (AIM) structureoft he muon-substituted malonaldehyde and the AIM structureo ft he stable and the transition-state configurations of malonaldehyde also unequivocally demonstrates substantial similarities of the muon-substituted malonaldehydet ot he transition state.

show abstract

“…wide-gap semiconductors, insulating systems or cuprate and iron-based high-T c superconductors. [20][21][22][23][24][25] There are four equivalent minima in the unit cell corresponding to the 4c [(x, 1/4, z), x µ = 0.103, z µ = 0.921] Wyckoff position (see the Supplementary part). The calculations were started from the known FM and Hel−c magnetic structures at ambient pressure (see Refs.…”

Section: 7mentioning

confidence: 99%

High-pressure magnetic state of MnP probed by means of muon-spin rotation

et al. 2016

Self Cite

View full text Add to dashboard Cite

We report a detailed µSR study of the pressure evolution of the magnetic order in the manganese based pnictide MnP, which has been recently found to undergo a superconducting transition under pressure once the magnetic ground state is suppressed. Using the muon as a volume sensitive local magnetic probe, we identify a ferromagnetic state as well as two incommensurate helical states (with propagation vectors Q aligned along the crystallographic c− and b−directions, respectively) which transform into each other through first order phase transitions as a function of pressure and temperature. Our data appear to support that the magnetic state from which superconductivity develops at higher pressures is an incommensurate helical phase.

show abstract

Ab initiostrategy for muon site assignment in wide band gap fluorides

Cited by 64 publications

References 40 publications

Efficient and Reliable Strategy for Identifying Muon Sites Based on the Double Adiabatic Approximation

Efficient and Reliable Strategy for Identifying Muon Sites Based on the Double Adiabatic Approximation

Muon‐Substituted Malonaldehyde: Transforming a Transition State into a Stable Structure by Isotope Substitution

High-pressure magnetic state of MnP probed by means of muon-spin rotation

Contact Info

Product

Resources

About