Figure 3: [(tpa^Ph)Fe]⁻ ab initio spin dynamics results.

Calculated temperature dependence of the relaxation time, τ. Black dots are for simulations where all the relaxation processes are considered. The green triangles and the green line represent the experimental results as taken from ref. 25. The blue and red lines represent calculations performed, respectively, by considering only transitions between the quasi-degenerate doublet, and by completely neglecting them (that is, by considering only relaxation processes activated through the excited states). Arrhenius’s fits performed for the T<5 K and for 5 K<T<10 K cases return effective barriers of 19.7 cm⁻¹ and 55.7 cm⁻¹, respectively. In the inset, we show the relaxation time in the high-T range calculated using only a limited number of phonon modes when all the relaxation processes are included. The red line with squares describes the simulation done with only five modes, the blue line with diamonds corresponds to the simulation done with 15 modes and the black line with dots corresponds to the full-phonon spectra case.