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SUMMARY:Muon Sites in Hexagonal Ice
DTSTART;VALUE=DATE-TIME:20220830T152000Z
DTEND;VALUE=DATE-TIME:20220830T170000Z
DTSTAMP;VALUE=DATE-TIME:20220826T120829Z
UID:indico-contribution-3876@indico.stfc.ac.uk
DESCRIPTION:Speakers: Amba Datt Pant (IMSS\, KEK\, Japan)\nTheoretical stu
 dy using density functional theory (DFT) calculations supports to estimate
  the stopping site of muon in materials and understand the muon spin rotat
 ion and relaxation ($\\mu$SR) measurements. To understand the temperature 
 dependent zero-field (ZF) $\\mu$SR measurement in water\, we have performe
 d DFT calculations and quantum simulation to estimate the muon sites in he
 xagonal (Ih) ice. Taking initial lattice parameters from the high-resoluti
 on neutron powder diffraction study [1]\, the muon stopping site was calcu
 lated in the Ih supercell containing 2×2×1 conventional cells using Quan
 tum ESPRESSO [2]. The supercell contains 12 water molecules and a muon. Th
 e added muon in Ih ice behaves as a defect in a solid which leads to the r
 elaxation of immediate surrounding structure. The water molecules nearby t
 he muon site found reoriented. The stopping site of muon is found at aroun
 d 2 A distance from three protons (one proton of a water molecule and two 
 of another\, total four spin-half (4S) system). It seems like H$_2$O-Mu-H$
 _2$O$^+$ but the muon site is found neither L-defect nor D-defect but like
  interstitial. Based on this result and quantum simulation [4]\, only the 
 slow-oscillating term of ZF spectra at 270 K can reproduce. To satisfy the
  fast-oscillating term of the ZF spectra\, quantum simulation indicates th
 at the muon should be at least 0.99 A distance from one of the protons in 
 the 4S system (indicating two sites of muon). In the program\, we will pre
 sent DFT calculations and quantum simulations to interpret the oscillating
  ZF spectra at 270 K. \n\n[1] A. D. Fortes\, *Acta Crystallographica Secti
 on* B **74** (2018) 196.\n[2] P. Giannozzi\, et al.\, *Journal of Physics:
  Condensed Matter* **21** (2009) 395502.\n[3] B. G. Pfrommer\, et al.\, *J
 ournal of Computational Physics* **131** (1997) 233.\n[4] J. Lord\, *Physi
 ca B: Condensed Matter* **374-375** (2006) 472.\n\nhttps://indico.stfc.ac.
 uk/event/53/contributions/3876/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3876/
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