比如在http://arxiv.org/pdf/1311.1646v1.pdf提到过 a way was found to construct the linear response space for general choices of the MPS gauge in terms of the tangent space vectors
涉及了 tangent space vectors,
在http://arxiv.org/pdf/1405.1225.pdf提到了Grassmann manifold "An SD is therefore described by the Grassmann manifoldUL/(UN × UL−N ), with Uk the unitary group of k × k unitary matrices."
