Investigation of the influence of chirality and frustration on magnetic properties of large molecule-based spin systems withDynamical Density Matrix Renormalization Group and relate methods

我们的主要目标是评估在基态(T=0)、低激发态(即极低温度)和外加磁场下的感兴趣的大分子自旋系统的光谱函数。这些光谱函数应与实验INS光谱进行比较。我们要了解它的物理性质，并推导出相关哈密顿量的参数。从技术上讲，我们使用(动力学)密度矩阵重整化群和Lanczos方法。我们可以在以前的研究中证明，这些方法允许以前所未有的精度推导哈密顿参数。使用这些方法并与我们的实验伙伴合作，我们想要研究几种物质。其中一类由两个自旋管组成，它们类似于卷起的三角形晶格。在这里，我们想要更好地了解它们在磁场中的行为，并研究可能的Dzyaloshinskii-Moriya相互作用的影响。另一类是类似于Kagome晶格的Keplerate分子{Mo72V30}和{W72V30}。多亏了S=1/2的小钒自旋，它们才能被准精确地处理。这两类都是高度受挫的自旋系统，具有不寻常的激发光谱。对于Keplerates，我们计划将我们的研究扩展到更大的自旋。另一个重点将是螺旋系统，这些系统很有趣，INS非常适合。我们期望各向异性稳定的手征磁态。用一句话概括我们的目标：我们想要研究手性和受挫对大分子自旋系统磁性的影响。当然，我们计划将我们合作伙伴的新化合物纳入我们的研究。

The principal goal consists in the evaluation of spectral functions of interesting large molecule-based spin systems in the ground state (T=0) and for low-lying excited states, i.e. very low temperatures, and for applied magnetic fields. These spectral function shall be compared with experimental INS spectra. We would to understand the physical properties and to derive the parameters of the relevantHamiltonian. Technically we use (Dynamical) Density Matrix renormalization Group and Lanczos methods. We could show in previous studies that these allow to deduce Hamiltonian parameters with unprecedented accuracy.Using these methods and in collaboration with our experimental partners we would like to study several substances. One class consists in two spin tubes that are similar to rolled-up triangular lattices. Here we would like to better understand their behaviour in a magnetic field and investigate the influence of a possible Dzyaloshinskii-Moriya interaction. Another class is given by the Keplerate molecules {Mo72V30} and {W72V30} which are similar to the Kagome lattice. Thanks to the small vanadium spin of s=1/2 they can be treated quasi exactly. Both classes are highly frustrated spin systems with unusual excitation spectra. For Keplerates we plan to extend our investigations to larger spins.Another focus will be given by helical systems, that are interesting and for which INS is well-suited. We expect chiral magnetic states stabilized by anisotropy. To summarize our goals in one sentence: we want to investigate the influence of chirality and frustration on magnetic properties of large molecule-based spin systems. Of course we plan to incorporate new compounds of our partnersinto our investigations.