Atomistic calculation of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>τ</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math> inverse attempt frequency in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow

The Arrhenius law predicts transition times between equilibrium states in thermally activated systems, with broad interdisciplinary relevance. In paleomagnetism, it is used to estimate relaxation times and the thermal stability of magnetic nanoparticles. Magnetite, key to both paleomagnetic studies and magnetic hyperthermia, shows large uncertainties in its attempt frequency <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>f</a:mi><a:mn>0</a:mn></a:msub></a:math>, varying over <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:msup><b:mn>10</b:mn><b:mn>7</b:mn></b:msup><b:mo>–</b:mo><b:msup><b:mn>10</b:mn><b:mn>13</b:mn></b:msup><b:mspace width="0.16em"/><b:mi>Hz</b:mi></b:mrow></b:math> and affecting relaxation rate estimates. We present a dynamical method using atomistic spin dynamics to fully parametrize the Arrhenius-Néel law. For magnetite nanoparticles with cubic anisotropy, we find <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi>τ</d:mi><d:mn>0</d:mn></d:msub><d:mo>=</d:mo><d:mn>0.98</d:mn><d:mo>±</d:mo><d:mn>0.13</d:mn><d:mspace width="0.16em"/><d:mi>ns</d:mi></d:mrow></d:math> at room temperature. For particles with enhanced anisotropy, <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msub><f:mi>τ</f:mi><f:mn>0</f:mn></f:msub></f:math> decreases significantly and shows a different temperature dependence, highlighting the role of anisotropy. Our method applies to a broad range of systems with clearly defined states and enables robust estimates of domain stability, with particular relevance for the micromagnetic analysis of paleomagnetic records and improving our understanding of geomagnetic fidelity over geological time.