rganic radicals. It is inaccurate for transition metal complexes, e.g. Cu<sup>2+</sup> or VO<sup>2+</sup>. For the diffusion, both secular and nonsecular terms are included.
</p>

<p>
If the spin system has S=1/2 and contains no more than two nuclei, <code>chili</code> by default uses a fast method to construct the Liouvillian matrix that uses code based on the software from the Freed lab at Cornell (<code>Opt.Method='fast'</code>). For all other cases, a general code is used to construct the Liouvillian ma