MuFinder: A program to determine and analyse muon stopping sites

Abstract

Significant progress has recently been made in calculating muon stopping sites using density functional theory. The technique aims to address two of the most common criticisms of the muon-spin spectroscopy (µ + SR) technique, namely, where in the sample does the muon stop, and what is its effect on its local environment. We have designed and developed a program called MuFinder that enables users to carry out these calculations through a simple graphical user interface (GUI). The procedure for calculating muon sites by generating initial muon positions, relaxing the structures, and then clustering and analysing the resulting candidate sites, can be done entirely within the GUI. The local magnetic field at the muon site can also be computed, allowing the connection between the muon sites obtained and experiment to be made. MuFinder will make these computations significantly more accessible to non-experts and help to establish muon site calculations as a routine part of µ + SR experiments.

Radio-frequency manipulation of state populations in an entangled fluorine-muon-fluorine system

“…To determine the µ + stopping site and associated lo-cal structural distortion within the crystal [6,7,13] first-principles calculations [14][15][16] were performed. We found a unique minimum energy structural configuration in which the two nearest-neighbors of the µ + are both F − ions (forming a state resembling F-µ-F) the two next-nearest-neighbors are both Li + ions and the two next-next-nearest-neighbors are both F − .…”