Elmer Doggen

You're welcome. Do you intend to implement the one-site algorithm at any point?

Just to add to this point: to stay in the same variational manifold, one must apply the one-site algorithm (this is also what evoMPS does), whereas you are using a two-site approach. See arXiv:1809.01400

Just to come back to this issue: it looks like the non-conservation of energy in your TDVP implementation is quite general, except when you time-evolve with unrestricted bond dimension for small systems (e.g. bond dimension 32 for L = 10 and a spin-1/2 problem). The conservation of energy in the TDVP time step requires that you stay within the same MPS manifold. If you choose an unrestricted bond dimension, then the MPS manifold cannot change (after all, it contains the entire Hilbert space of the...

I am trying to simulate time dynamics using your implementation of the time-dependent variational principle (TDVP). My Hamiltonian contains only on-site and nearest-neighbour terms, so I can compare to TEBD, also using your implementation. Surprisingly, TEBD seems to do a better job for the long-time dynamics (I simulated up to t = 100 in standard lattice units, using a timestep 0.1), in the following sense. I perform a quench of a Hamiltonian parameter instantenously, and allow the system to evolve...

I am trying to simulate time dynamics using your implementation of the time-dependent variational principle (TDVP). My Hamiltonian contains only on-site and nearest-neighbour terms, so I can compare to TEBD, also using your implementation. Surprisingly, TEBD seems to do a better job for the long-time dynamics (I simulated up to t = 100 in standard lattice units, using a timestep 0.1), in the following sense. I perform a quench of a Hamiltonian parameter instantenously, and allow the system to evolve...