### Choosing dt for time evolve

Posted:

**05 Dec 2023, 04:09**Hi,

I am doing a periodic boundary Ising model with N sites (say 40 sites) and I am time evolving with the following code:
It turns out that the quantities of my interest are converging to different values for different choices of dt.

What should I keep in mind to choose dt for N (say 40) sites? What choice of dt ensures that my results converge to the same value?

Thanks.

I am doing a periodic boundary Ising model with N sites (say 40 sites) and I am time evolving with the following code:

Code: Select all

```
#Time evolution parameters
evol_params = {
'N_steps':1,
'compression_method': 'SVD', ### same results for 'SVD' and 'variational'
'trunc_params': {"chi_max": chi,"svd_min": 1e-10,},
'dt':dt,
}
evol = mpo_evolution.ExpMPOEvolution(psi, M, evol_params)
for t in range(t_max):
psi_t = evol.run()
```

What should I keep in mind to choose dt for N (say 40) sites? What choice of dt ensures that my results converge to the same value?

Thanks.