Magnetic nanoparticles have the potential to be used in various biomedical applications, including magnetic drug targeting and hyperthermia for cancer treatment. In both cases, precise prediction of the local particle concentration is required to plan a successful therapy, which is a challenging task due to several complex flow phenomena. Computational macroscopic and microscopic models have been developed to support this process, but they have limitations in terms of interactions implementation, micromagnetic dynamics or computational costs. This study aims to develop a model that can represent micromagnetic dynamics and being employed to study equilibrium properties of particle ensembles in viscous media. Therefore, a kinetic Monte Carlo method in combination with Langevin equations is used. So, magnetization dynamics and mechanical motion can be simulated in combination very efficiently. The new model is validated with another model based on the stochastic Landau-Lifshitz-Gilbert equation. Various interaction potentials like Van der Waals, steric and electrostatic interactions are included to study their specific influence on structural properties. Also, methods to control the errors while integrating the equations of motion and using the Ewald method for calculating interaction quantities are implemented. As a validation we studied equilibrium and time dependent properties of non-interacting particle ensembles as well as errors made by the Ewald-method used for interaction quantities calculation. In all studies we found very good agreement of the simulation results with the theoretical predictions. The developed models can now be used for investigating equilibrium and dynamic properties of ferrofluids, or more general for biomedical research for magnetic drug targeting, hyperthermia, or imaging techniques. Furthermore, the new hybrid model can be also used for simulations in the range of milliseconds with reasonable computational effort.

中文翻译：

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用于研究平衡和动态系综特性的相互作用磁性纳米粒子的分子动力学建模


磁性纳米颗粒具有用于各种生物医学应用的潜力，包括磁性药物靶向和用于癌症治疗的热疗。在这两种情况下，都需要精确预测局部颗粒浓度来计划成功的治疗，由于几种复杂的流动现象，这是一项具有挑战性的任务。已经开发了计算宏观和微观模型来支持这一过程，但它们在相互作用实现、微磁动力学或计算成本方面存在局限性。本研究旨在开发一种可以代表微磁动力学的模型，并用于研究粘性介质中粒子系综的平衡特性。因此，采用动力学蒙特卡罗方法与朗之万方程相结合。因此，可以非常有效地组合模拟磁化动力学和机械运动。新模型通过另一个基于随机 Landau-Lifshitz-Gilbert 方程的模型进行了验证。包括范德华力、空间相互作用和静电相互作用等各种相互作用势，以研究它们对结构特性的具体影响。此外，还实现了在积分运动方程和使用 Ewald 方法计算相互作用量时控制误差的方法。作为验证，我们研究了非相互作用粒子系综的平衡和时间相关特性，以及用于相互作用量计算的 Ewald 方法所产生的误差。在所有研究中，我们发现模拟结果与理论预测非常吻合。 开发的模型现在可用于研究铁磁流体的平衡和动态特性，或更一般地用于磁性药物靶向、热疗或成像技术的生物医学研究。此外，新的混合模型还可以通过合理的计算量进行毫秒范围内的模拟。