Coarse grained models for large scale atomistic simulations of spin and lattice dynamics

磁热材料系统中的耦合效应将通过密度泛函理论（DFT）、紧密结合和键序势方法进行研究。通过与合作伙伴的合作，我们希望对磁热材料的磁结构相变有深入的了解，并在此基础上对这类材料的优化做出贡献。在这个项目中，我们将开发具有足够精度的原子键序势，用于模拟磁热材料。这一目标将通过从精确的密度函数表示开始的电子结构的系统粗粒化来实现。键序势将允许O(N)分子动力学模拟，并且与DFT相比将增加额外的长度和时间尺度。这将允许模拟微观结构元素，如孪晶界和晶界的动力学，以及直接评估与磁结构相变相关的能量/熵贡献。此外，在与实验伙伴的密切合作中，我们将进行准确的所有电子计算，以优化已知和研究可能的新型磁热材料。研究了合金成分、应变和磁场对Y-Co - Ce-Fe基体系的影响。

Coupling effects in magnetocaloric materials systems will be investigated by density functional theory (DFT), tight binding and bond order potential methods. Through a cooperative effort with our partners in this package proposal we want to achieve an in-depth understanding of the magnetostructural phase transitions in magnetocaloric materials and based on this contribute to an optimization of this materials class. Within this project, we will develop atomistic bond order potentials with sufficient accuracy for the simulation of magnetocaloric materials. This goal will be achieved through a systematic coarse graining of the electronic structure starting from an accurate density functional representation. The bond order potential will allow for O(N) molecular dynamics simulations and will add an additional length and time scale compared to DFT. This will allow for the simulation of microstructure elements like the dynamics of twin and grain boundaries as well as for a direct evaluation of energetic/entropic contributions in connection with the magneto-structural phase transition. Furthermore, In a close collaboration with our experimental partners we will perform accurate all electron calculations in order to optimize known and investigate possible new magnetocaloric materials. The influence of alloy composition, strain and magnetic field will be studied for Y-Co Ce-Fe based systems.