converges in tdvp function

Hey all,
I am trying to do an non-unitary time evolution to my system and I am running with a warning:
“warning: applyexp not converged in 30 steps” after using the tdvp function. Is there any limitation about the delta t we can put in there ?

using ITensors
            ψ_τ= tdvp(H_syk,ψ_τ,-m)

where m can range from 1 to 10. I know that this is a very brute delta t, but I wanted to know if there is any way that I can time developing with a large m’s (even larger than that one) ?

You could try the exponentiate solver backend by including the keyword argument solver_backend="exponentiate". That will use the exponentiate function from KrylovKit.jl which is more sophisticated and uses restarts to allow you to reach longer times. Of course, if you use too large of a time step you will have higher projection error/Trotter error.

Hi. I am using C++ version of TDVP, is there similar things like solver_backend=“exponentiate” that exist there? I am just confused what that warning implies! Because I have tried my TDVP code with increasing sweeps.niter(), but that warning does not go away.

Sorry to hear you’re having an issue. Since this is an older post (from February) can you please post a new topic (you can still link to this one) and tell us more information, such as what time step size you are using?

Thank you for your reply. I have created a new topic for my query in the link.