Using HDF5 in DMRG.jl

[cfengno1]

Hi there,

I am trying to add a few lines of code that saves the psi to .h5 file during the DMRG sweeps. I add the following line to the top of dmrg.jl file:
using HDF5

but it reports the following error

  **ERROR:** LoadError: ArgumentError: Package ITensors does not have HDF5 in its dependencies:
- You may have a partially installed environment. Try `Pkg.instantiate()` to ensure all packages in the environment are installed.
- Or, if you have ITensors checked out for development and have added HDF5 as a dependency but haven't updated your primary environment's manifest file, try `Pkg.resolve()`.
- Otherwise you may need to report an issue with ITensors

Then, I tried to add HDF5 to the dependence of ITensor by running:

Pkg.activate("/home/cfengno1/.julia/dev/ITensors/")
Pkg.add("HDF5")
using ITensors

It gives the following error:

  **Warning:** The project dependencies or compat requirements have changed since the manifest was last resolved.
 It is recommended to `Pkg.resolve()` or consider `Pkg.update()` if necessary.
@ Pkg.API ~/.julia/juliaup/julia1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/Pkg/src/API.jl:1807

  **Precompiling** ITensors
  1 dependency successfully precompiled in 9 seconds. 91 already precompiled.

  **Warning:** The project dependencies or compat requirements have changed since the manifest was last resolved. It is recommended to `Pkg.resolve()` or consider `Pkg.update()` if necessary.@ Pkg.API ~/.julia/juliaup/julia-1.10.4+0.x64.linux.gnu/share/julia/stdlib/v1.10/Pkg/src/API.jl:1807

  **Info:** Precompiling ITensorsVectorInterfaceExt [2f1fcacd-197e-560a-aa0f-27cf761d5e85]

**Warning:** Module ITensorsVectorInterfaceExt with build ID ffffffff-ffff-ffff-00d9-4bce33645c6f is missing from the cache. This may mean ITensorsVectorInterfaceExt [2f1fcacd-197e-560a-aa0f-27cf761d5e85] does not support precompilation but is imported by a module that does.
 @ Base loading.jl:1948

  ** Error:** Error during loading of extension ITensorsVectorInterfaceExt of ITensors, use `Base.retry_load_extensions()` to retry.
 exception =
1-element ExceptionStack:
Declaring __precompile__(false) is not allowed in files that are being precompiled.

Can you help me to save the state psi to file in the middle of the DMRG sweeps?

Best,
Feng Chen

[kmp5]

Hi Feng,

I think it would be much safer to not modify the Project.toml of ITensor. Potentially a better idea is to make a custom Observer object which captures psi during a DMRG computations and writes it to disk there. That way your Observer code will interface with HDF5 and you will not need HDF5 in ITensors explicitly.
Additionally, I have found much better luck with using the JLD2 package over HDF5 for writing ITensors to disk.

All the best,
Karl

[cfengno1]

Thank you very much Karl!