Hi，

when I tried to use single site dmrg (Electron)

```
auto [Energy, psi] = dmrg(H, psi0, sweeps, {"Quiet=", true, "NumCenter=", 1});
```

I encountered the following problem:

From line 137, file ITensor/itensor/iterativesolvers.h

davidson: size of initial vector should match linear matrix size.

dim(inds(phi.front())) = 16

A.size() = 4

davidson: size of initial vector should match linear matrix size.

How can I solve it?