Hi everyone and happy new year,

It's just a syntax question but the answer would be very useful for me, in order to simplify my code.

I simulate a model with plaquette-like interactions on a Ladder with terms of

of the type sigma*{i,x} \prod*{j neighbors of i } Proj_{j,up}.

This means that I have to construct autoMPO terms with variable number of involved operators (due to boundaries)

Is there a way to construct each term of the Hamiltonian via concatenation?

### Pseudo-code:

```
for (site 1)
term = coeff; //Real number
term = concatenate(term,op1,site1);
if (condition site 2 met)
term = concatenate(term,op2,site2);
if (condition site 3 met)
term = concatenate(term,op3,site3);
ampo += term;
```

Benoit