# Classical spin simulations with a quantum two-spin correction

## TL;DR

This paper introduces a quantum correction to classical spin simulations to better model nuclear spin dynamics in solids, especially when the number of interacting neighbors is small, but faces challenges at longer times.

## Contribution

The authors propose adding a two-spin quantum correlation term to classical simulations, improving accuracy for small neighbor interactions in spin chains.

## Key findings

- Improved short-time accuracy in spin dynamics simulations.
- Classical plus quantum correction method shows limitations at long times.
- Method tested on a spin-1/2 chain with promising results at short times.

## Abstract

Classical simulations of high-temperature nuclear spin dynamics in solids are known to accurately predict relaxation for spin 1/2 lattices with a large number of interacting neighbors. Once the number of interacting neighbors becomes four or smaller, classical simulations lead to noticeable discrepancies. Here we attempt to improve the performance of the classical simulations by adding a term representing two-spin quantum correlations. The method is tested for a spin-1/2 chain. It exhibits good performance at shorter times, but, at longer times, it is hampered by a singular behavior of the resulting equations of motion.