Elaborate search of exotic phases and level spectroscopy in quantum spin chains

能级光谱学是本课题组开发的一种分析量子自旋链数值数据以非常精确地找到量子临界点的方法。我们将能级光谱学方法应用于几个模型中，以寻找奇异相，并获得精确的相图。对于各向异性的S=2量子自旋链，我们首次发现了中间d相，这是大约20年前提出的，多年来一直被认为不存在。对争论多年的蓝铜矿磁性参数问题也得到了确定性的结论。

The level spectroscopy is a method for analyzing the numerical data of quantum spin chains to find quantum critical points very accurately, which was developed by our group. We applied the level spectroscopy method to several models, to find exotic phases, and also to obtain precise phase diagrams. For the anisotropic S=2 quantum spin chain, we found the intermediate-D phase for the first time, which was proposed about 20 years ago and has been thought to be absent for long years. Also we obtained a deterministic conclusion for the parameter problem of the magnetism of azurite, which has been in controversy for many years.