Quantum behaviour of hydrogen and muonium in vacancy-containing complexes indiamond

Abstract

Most solid-state electronic structure calculations are based on quantumelectrons and classical nuclei. These calculations either omit quantum zero-pointmotion and tunnelling, or estimate it in an extra step. Such quantum effectsare especially significant for light nuclei, such as the proton or its analogue,μ+. We propose a simple approach to including such quantum behaviour, in a form readilyintegrated with standard electronic structure calculations. This approach is demonstrated for anumber of vacancy-containing defect complexes in diamond. Our results suggest that for theNHV− complex, quantum motion of the proton between three equivalent potential energyminima is sufficiently rapid to time-average measurements at X-band frequencies.