MRC Special Edition on Quantum-Chemical Computations of Magnetic Resonance Parameters

Abstract

Methods for first-principles computation of NMR chemical shifts and EPR hyperfine coupling constants have long been part of the computational chemist's toolkit, with J-couplings and g-tensors as more recent additions. Considerable experience concerning the accuracy and performance of the various quantum-chemical models for these parameters has been accumulated by now, so that in many cases calculation of the key features of NMR or EPR spectra is becoming increasingly routine. This is especially true with the advent of efficient methods rooted in density functional theory and the unabated developments in computer hardware, which make ever larger, more “realistic” systems amenable to first-principles calculations. The fraction of papers reporting applications of such computations, either stand-alone or jointly with experimental results, is steadily increasing in all areas of chemistry. Because Magnetic Resonance in Chemistry is no exception to this development, the idea arose to dedicate a whole issue of the journal to this topic. As mentioned above, in many aspects the computation of magnetic resonance parameters is a mature field by now. A lot of challenges remain, however, such as the reliable modeling of environmental effects on the properties of interest. For example, how are the intrinsic NMR or EPR parameters of a molecule or an ion affected by embedding in a dynamic ensemble of polar solvent or an extended crystal matrix? Development of new methods and their validation for this purpose continues to be an active area of research. Another question often posed to theory is, why do the recorded magnetic resonance parameters adopt their particular values or follow the observed trends? The more sophisticated the underlying quantum-mechanical models get, the more difficult it often becomes to gain such insights that transcend the bare numbers. Again, special interpretative, computational tools need to be developed, tested and applied for this purpose. The present Special Issue is an attempt to provide a representative snapshot of the vibrant field of NMR and EPR computations and their applications, including some reviews of the latest developments pursued in some of the leading groups around the world. Special attention is called to periodic NMR calculations for infinite solids, an area where experiment and theory can team up in an especially fruitful way. There has been increasing interest in this field, particularly among the experimental community, and the use of calculation to support and interpret experimental results in the solid state is becoming increasingly common in many laboratories. We like to thank all the authors for their response to our call, the production team at Wiley for smooth processing of the manuscripts, as well as James Keeler, Martin McLean and Arwen Tapping for inviting us as guest editors and for their constant help along the way.