MuFinder: A program to determine and analyse muon stopping sites

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.

近年来，利用密度泛函理论（density functional theory）计算μ子停止位点的研究已取得显著进展。该技术旨在回应μ子自旋光谱学（muon-spin spectroscopy，μ^+SR）领域两项最为常见的批评性质疑：一是μ子在样品中的具体停留位置，二是其对局部环境所产生的影响。我们设计并开发了一款名为MuFinder的程序，用户可通过其简洁易用的图形用户界面（graphical user interface，GUI）完成此类计算。整套μ子位点计算流程——涵盖生成初始μ子位置、弛豫晶体结构、继而对所得候选位点进行聚类与分析——均可在该GUI内一站式完成。此外，程序还支持计算μ子位点处的局域磁场，从而搭建起所预测的μ子位点与实验结果之间的关联桥梁。MuFinder将大幅降低非专业研究者开展此类计算的门槛，助力将μ子位点计算确立为μ^+SR实验的常规研究环节。