Efficient Method for the Simulation of high-temperature Spin Dynamics*

The measurements of nuclear free induction decays (FIDs) can be used to extract microscopic information about solids such as the distances between nuclear spins or electronic spin susceptibility. At the same time, the first-principles calculation of solid FIDs, which is important for such an extraction, is a long-standing problem.
We propose a new hybrid quantum-classical method for the first-principles calculation of solid FIDs, which is based on simulating a large quantum spin lattice by a small cluster of quantum spins coupled to an environment of interacting classical spins via a correlation-preserving scheme. The hybrid method is applied to the computation of FIDs in real materials, such as: CaF₂, ²⁹Si-enriched crystalline silicon and fluorapatite. In all the cases, excellent agreement with the experiment is observed.
References:
[1] G. A. Starkov and B. V. Fine, Phys. Rev. B 98, 214421 (2018)
[2] G. A. Starkov, "Simulations of High-Temperature Spin Dynamics", Ph.D. thesis,
Skolkovo Institute of Science and Technology (2019),
available at https://www.skoltech.ru/app/data/uploads/2019/10/THESIS_STARKOV.pdf.