Code: Select all

```
/TeNPy/tenpy/algorithms/dmrg.py:523: UserWarning: final DMRG state not in canonical form within `norm_tol` = 1.00e-06
warnings.warn(msg.format(nt=norm_tol))
```

Code: Select all

```
dmrg_params = {
'mixer': True,
'mixer_params': {'amplitude': 1.e-5, 'decay': 1.2, 'disable_after': 30},
'trunc_params': {
# 'chi_max': chi_max,
'svd_min': 1.e-10
},
# 'lanczos_params': {
# 'reortho': True,
# 'N_cache': 40
# },
'chi_list': {0: 9, 10: 49, 20: 100, 40: 600},
# 'max_E_err': 1.e-10,
# 'max_S_err': 1.e-6,
'norm_tol': 1.e-6,
'norm_tol_iter': 1000,
# 'max_sweeps': 150,
'verbose': 1,
'N_sweeps_check': 10
}
```

1) Should specifying "norm_tol", without specifying "norm_tol_iter", keep the simulation running indefinitely until the desired norm_tol has been reached?

2) Why is my simulation stopping in less than 1000 sweeps without having reached my desired norm_tol?

3) How to reliably ensure that my final DMRG state is in canonical form?

For reference, here is the final verbose output from one of my simulations with these DMRG parameters:

Code: Select all

```
sweep 270, age = 60030
Energy = -0.9591375409272587, S = 1.9900301579609951, norm_err = 2.8e-04
Current memory usage 1792.1 MB, time elapsed: 2167.6 s
Delta E = 3.9906e-09, Delta S = 6.4814e-06 (per sweep)
max_trunc_err = 3.3170e-08, max_E_trunc = 5.5070e-07
MPS bond dimensions: [600, 600, 600, 600, 600, 600]
norm_tol=1.00e-06 not reached, norm_err=2.80e-04
```