An overview of first-principles calculations of NMR parameters for paramagnetic materials

Abstract

Many technologically important materials exhibit paramagnetism, for example, lithium intercalation materials for lithium-ion batteries and platinum nanoparticles for catalysis. In order to study their properties, for example, their electron transport properties or catalytic efficiency, and hence tailor them to specific engineering applications, information on their structure and bonding needs to be acquired. Solid state nuclear magnetic resonance (NMR) is an excellent experimental method for achieving this; however, the resulting spectra are often difficult to interpret. Calculations based on quantum mechanics therefore provide an invaluable aid for decoding these experimental spectra. The dominant interaction in paramagnetic materials is the hyperfine interaction. This is the interaction between the spin of a nucleus and the spin of an unpaired electron. The hyperfine interaction affects the appearance of NMR spectra, both by shifting the frequencies at which resonance occurs and by removing degeneracies so that a single resonance frequency splits into several frequencies. This review examines the methods and current limitations for calculating hyperfine interaction parameters, placing this in the context of experimental NMR investigations for lithium intercalation materials and platinum nanoparticles. In this way, the importance of developing increasingly accurate methods for calculating hyperfine parameters is illustrated.