title: Numerical simulation of free evolution in solid-state nuclear magnetic resonance using low-order correlations in Liouville space.
abstract: The design of simulations of free evolution in dipolar-coupled nuclear-spin systems using low-order correlations in Liouville space (LCL) is discussed, and a computational scheme relying on the Suzuki-Trotter algorithm and involving minimal memory requirements is described. The unusual nature of the approximation introduced by Liouville-space reduction in a spinning solid is highlighted by considering the accuracy of LCL simulations at different spinning frequencies, the quasiequilibria achieved by spin systems in LCL simulations, and the growth of high-order coherences in the exact dynamics. In particular, it is shown that accurate LCL simulations of proton spin diffusion occur in a regime where the reduced space excludes the coherences that make the dominant contribution to ∥σ∥(2), the norm-squared of the density matrix.
authors.affiliation: Université de Lyon (CNRS/ENS Lyon/UCB Lyon1), Centre de RMN à très hauts champs, 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Dumez
authors.forename: Mark C
authors.initials: MC
authors.lastname: Butler
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley