Hi everyone,

I am trying to get the MPO representation of H^2 from the one of H using the

nmultMPO function but I am unable to get the correct result. (Notice H is long ranged Hamiltonian) Below is the piece of code I am using:

```
auto sites = SpinHalf(N,{"ConserveQNs=",false}); //make a chain of N spin 1/2's
auto ampo = AutoMPO(sites);
for(auto i : range1(N-1))
{
for(auto j=i+1;j<=N;j++)
{
ampo += (i+j),"S+",i,"S-",j;
ampo += (i+j),"S-",i,"S+",j;
}
}
auto H = toMPO(ampo);
auto res= nmultMPO(H, H,{"Cutoff",1e-8});
```

I get the following error:

libc++abi.dylib: terminating with uncaught exception of type itensor::ITError: doTask not defined for task Mult and storage type Combiner

Your help will be greatly appreciated.

Regards,

Yas