## Problem with Delta E in iDMRG logs

How do I use this algorithm? What does that parameter do?
Michele
Posts: 3
Joined: 20 May 2023, 11:14

### Problem with Delta E in iDMRG logs

Hi everyone! I am seeing something quite confusing in the logs when I use iDMRG.
I am currently studying the following Hamiltonian:

$$H = \: - \: t_1 \sum_{\langle i,j \rangle , i<j} \left( b_i^{\dag} b_j + b_j^{\dag} b_i\right) \: - \: t_2 \sum_{\langle \langle i,j \rangle \rangle , i<j-1} \left( b_i^{\dag} b_j + b_j^{\dag} b_i\right) + \: V \sum_{\langle i,j \rangle , i<j} n_i n_j \: + \: \frac{U}{2} \sum_i n_i \left( n_i - 1 \right)$$

which is expected to have chiral supersolid ground-state in a certain region of the parameters space.
When I consider parameters in the Mott insulator region, in the CDW region and in the chiral superfluid region, everything seems to work smoothly, but when I choose parameters in the chiral supersolid regime I get only positive Delta E in the logs, while the Delta S is still positive. An example is shown below (I copied only the first few checkpoints in order for this to be not too long, but nothing changes even for higher values of the bond dimension):
BoseHubbardChain_nnn: set conserve to N
[2, 0, 2, 0]
Subconfig 'trunc_params'=Config(<2 options>, 'trunc_params') for config TwoSiteDMRGEngine
Reading 'chi_list'={0: 200, 20: 300, 40: 400, 60: 500, 80: 600, 100: 700, 120: 800} for config TwoSiteDMRGEngine
Setting chi_max = 200
Initial sweeps...
Updating environment
.
Subconfig 'mixer_params'=Config(<4 options>, 'mixer_params') for config TwoSiteDMRGEngine
disable mixer after 5 sweeps, final amplitude 1.32e-07
Updating environment
.....
================================================================================
sweep 10, age = 132
Energy = 0.2350331935560330, S = 1.4878139788221434, norm_err = 7.2e-03
Current memory usage 585.0 MB, time elapsed: 48.7 s
Delta E = nan, Delta S = nan (per sweep)
max_trunc_err = 5.5310e-10, max_E_trunc = 2.4826e-08
MPS bond dimensions: [200, 200, 200, 200]
Setting chi_max = 300
Updating environment
.....
================================================================================
sweep 20, age = 252
Energy = 0.2350846767108337, S = 1.6054033832777495, norm_err = 3.6e-03
Current memory usage 585.0 MB, time elapsed: 86.8 s
Delta E = 5.1483e-06, Delta S = 1.1759e-02 (per sweep)
max_trunc_err = 5.0950e-09, max_E_trunc = 2.0571e-07
MPS bond dimensions: [200, 200, 200, 200]
Updating environment
.....
================================================================================
sweep 30, age = 372
Energy = 0.2350939280185873, S = 1.6720224013943410, norm_err = 2.4e-03
Current memory usage 585.0 MB, time elapsed: 118.0 s
Delta E = 9.2513e-07, Delta S = 6.6619e-03 (per sweep)
max_trunc_err = 1.8232e-09, max_E_trunc = 7.5032e-08
MPS bond dimensions: [300, 300, 300, 300]
Setting chi_max = 400
Updating environment
.....
================================================================================
sweep 40, age = 492
Energy = 0.2350972320422002, S = 1.7187494430922099, norm_err = 1.7e-03
Current memory usage 585.0 MB, time elapsed: 153.3 s
Delta E = 3.3040e-07, Delta S = 4.6727e-03 (per sweep)
max_trunc_err = 3.5527e-09, max_E_trunc = 1.4307e-07
MPS bond dimensions: [300, 300, 300, 300]
Updating environment
.....
================================================================================
sweep 50, age = 612
Energy = 0.2350984352771448, S = 1.7545752836424748, norm_err = 1.3e-03
Current memory usage 585.0 MB, time elapsed: 205.2 s
Delta E = 1.2032e-07, Delta S = 3.5826e-03 (per sweep)
max_trunc_err = 1.3918e-09, max_E_trunc = 5.6872e-08
MPS bond dimensions: [400, 400, 400, 400]
Setting chi_max = 500
Updating environment
.....
================================================================================
Now, here is the same simulation done with finite-size DMRG and it doesn't show this problem in the logs:
BoseHubbardChain_nnn: set conserve to N
Subconfig 'trunc_params'=Config(<2 options>, 'trunc_params') for config TwoSiteDMRGEngine
Reading 'chi_list'={0: 250, 5: 350, 10: 450, 15: 500} for config TwoSiteDMRGEngine
Setting chi_max = 250
Subconfig 'mixer_params'=Config(<4 options>, 'mixer_params') for config TwoSiteDMRGEngine
================================================================================
sweep 1, age = 101
Energy = 40.0991954558993626, S = nan, norm_err = 1.0e+00
Current memory usage 581.1 MB, time elapsed: 80.0 s
Delta E = nan, Delta S = 0.0000e+00 (per sweep)
max_trunc_err = 1.3399e-06, max_E_trunc = 3.4106e-13
MPS bond dimensions: [3, 20, 55, 110, 191, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 99, 25, 5]
================================================================================
sweep 2, age = 101
Energy = 32.0363628406691632, S = nan, norm_err = 8.4e-01
Current memory usage 581.1 MB, time elapsed: 249.4 s
Delta E = -8.0628e+00, Delta S = 0.0000e+00 (per sweep)
max_trunc_err = 3.5095e-06, max_E_trunc = 5.2914e-11
MPS bond dimensions: [5, 25, 112, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 121, 25, 5]
disable mixer after 3 sweeps, final amplitude 2.96e-07
================================================================================
sweep 3, age = 101
Energy = 31.0006839417729729, S = nan, norm_err = 2.8e-03
Current memory usage 581.1 MB, time elapsed: 342.6 s
Delta E = -1.0357e+00, Delta S = 0.0000e+00 (per sweep)
max_trunc_err = 8.9517e-09, max_E_trunc = 1.2091e-08
MPS bond dimensions: [5, 25, 113, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 122, 25, 5]
================================================================================
sweep 4, age = 101
Energy = 31.0006824934765923, S = 1.3671428631901328, norm_err = 1.7e-05
Current memory usage 581.1 MB, time elapsed: 387.4 s
Delta E = -1.4483e-06, Delta S = nan (per sweep)
max_trunc_err = 2.9209e-10, max_E_trunc = 1.1720e-08
MPS bond dimensions: [5, 25, 120, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 121, 25, 5]
Setting chi_max = 350
================================================================================
sweep 5, age = 101
Energy = 31.0006824932845753, S = 1.3671447682393696, norm_err = 5.4e-08
Current memory usage 581.1 MB, time elapsed: 435.8 s
Delta E = -1.9202e-10, Delta S = 1.9050e-06 (per sweep)
max_trunc_err = 2.8268e-10, max_E_trunc = 1.2561e-08
MPS bond dimensions: [5, 25, 120, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, 121, 25, 5]
================================================================================
sweep 6, age = 101
Energy = 31.0006818785738076, S = 1.3671468348922078, norm_err = 3.0e-08
Current memory usage 581.1 MB, time elapsed: 504.0 s
Delta E = -6.1471e-07, Delta S = 2.0667e-06 (per sweep)
max_trunc_err = 3.8292e-11, max_E_trunc = 1.7481e-09
MPS bond dimensions: [5, 25, 122, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 125, 25, 5]
================================================================================
sweep 7, age = 101
Energy = 31.0006818773957527, S = 1.3671471792345793, norm_err = 7.7e-09
Current memory usage 581.1 MB, time elapsed: 578.4 s
Delta E = -1.1781e-09, Delta S = 3.4434e-07 (per sweep)
max_trunc_err = 3.8993e-11, max_E_trunc = 1.8044e-09
MPS bond dimensions: [5, 25, 125, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 121, 25, 5]
================================================================================
sweep 8, age = 101
Energy = 31.0006818773862456, S = 1.3671471951706093, norm_err = 7.3e-09
Current memory usage 581.1 MB, time elapsed: 651.8 s
Delta E = -9.5071e-12, Delta S = 1.5936e-08 (per sweep)
max_trunc_err = 3.9127e-11, max_E_trunc = 1.8119e-09
MPS bond dimensions: [5, 25, 118, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 117, 25, 5]
================================================================================
sweep 9, age = 101
Energy = 31.0006818773794315, S = 1.3671471966571584, norm_err = 7.2e-09
Current memory usage 581.1 MB, time elapsed: 729.3 s
Delta E = -6.8141e-12, Delta S = 1.4865e-09 (per sweep)
max_trunc_err = 3.9175e-11, max_E_trunc = 1.8140e-09
MPS bond dimensions: [5, 25, 121, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 120, 25, 5]
Setting chi_max = 450
================================================================================
sweep 10, age = 101
Energy = 31.0006818773673416, S = 1.3671471969458056, norm_err = 7.2e-09
Current memory usage 581.1 MB, time elapsed: 805.9 s
Delta E = -1.2090e-11, Delta S = 2.8865e-10 (per sweep)
max_trunc_err = 3.9278e-11, max_E_trunc = 1.8167e-09
MPS bond dimensions: [5, 25, 119, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 350, 117, 25, 5]
================================================================================
sweep 11, age = 101
Energy = 31.0006818012890655, S = 1.3671474681036526, norm_err = 5.9e-09
Current memory usage 581.1 MB, time elapsed: 899.8 s
Delta E = -7.6078e-08, Delta S = 2.7116e-07 (per sweep)
max_trunc_err = 8.2663e-12, max_E_trunc = 3.8905e-10
MPS bond dimensions: [5, 25, 120, 375, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 373, 119, 25, 5]
================================================================================
sweep 12, age = 101
Energy = 31.0006818011426475, S = 1.3671475138076716, norm_err = 2.3e-09
Current memory usage 581.1 MB, time elapsed: 1004.2 s
Delta E = -1.4642e-10, Delta S = 4.5704e-08 (per sweep)
max_trunc_err = 8.4236e-12, max_E_trunc = 3.9919e-10
MPS bond dimensions: [5, 25, 121, 374, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 368, 117, 25, 5]
================================================================================
sweep 13, age = 101
Energy = 31.0006818011408214, S = 1.3671475171565268, norm_err = 2.2e-09
Current memory usage 581.1 MB, time elapsed: 1107.1 s
Delta E = -1.8261e-12, Delta S = 3.3489e-09 (per sweep)
max_trunc_err = 8.4924e-12, max_E_trunc = 4.0214e-10
MPS bond dimensions: [5, 25, 116, 367, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 371, 117, 25, 5]
================================================================================
sweep 14, age = 101
Energy = 31.0006818011426759, S = 1.3671475177942687, norm_err = 2.2e-09
Current memory usage 581.1 MB, time elapsed: 1209.4 s
Delta E = 1.8545e-12, Delta S = 6.3774e-10 (per sweep)
max_trunc_err = 8.5152e-12, max_E_trunc = 4.0324e-10
MPS bond dimensions: [5, 25, 116, 363, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 367, 117, 25, 5]
Setting chi_max = 500
================================================================================
sweep 15, age = 101
Energy = 31.0006818011444842, S = 1.3671475180987616, norm_err = 2.1e-09
Current memory usage 581.1 MB, time elapsed: 1314.3 s
Delta E = 1.8083e-12, Delta S = 3.0449e-10 (per sweep)
max_trunc_err = 8.5306e-12, max_E_trunc = 4.0392e-10
MPS bond dimensions: [5, 25, 116, 361, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 450, 367, 117, 25, 5]
================================================================================
sweep 16, age = 101
Energy = 31.0006817913131165, S = 1.3671475557482984, norm_err = 1.4e-09
Current memory usage 581.1 MB, time elapsed: 1429.5 s
Delta E = -9.8314e-09, Delta S = 3.7650e-08 (per sweep)
max_trunc_err = 4.2419e-12, max_E_trunc = 2.0576e-10
MPS bond dimensions: [5, 25, 116, 366, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 374, 117, 25, 5]
================================================================================
sweep 17, age = 101
Energy = 31.0006817913113011, S = 1.3671475611073398, norm_err = 1.1e-09
Current memory usage 581.1 MB, time elapsed: 1547.9 s
Delta E = -1.8154e-12, Delta S = 5.3590e-09 (per sweep)
max_trunc_err = 4.2807e-12, max_E_trunc = 2.0778e-10
MPS bond dimensions: [5, 25, 117, 363, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 370, 117, 25, 5]
================================================================================
sweep 18, age = 101
Energy = 31.0006817913109991, S = 1.3671475615017554, norm_err = 1.1e-09
Current memory usage 581.1 MB, time elapsed: 1671.4 s
Delta E = -3.0198e-13, Delta S = 3.9442e-10 (per sweep)
max_trunc_err = 4.2925e-12, max_E_trunc = 2.0810e-10
MPS bond dimensions: [5, 25, 117, 362, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 500, 370, 117, 25, 5]
================================================================================
Here both Delta E and Delta S are behaving correctly.
What is strange is that in the end both simulations output a final state that is a chiral supersolid, with same density profile (except at the border of the finite MPS of course), same long range correlations and double peaks in the momentum distribution, signaling chirality.

I should probably point out that I tried iDMRG simulation both with and without mixer, with extremely high values of chi_max and extremely low cut-off svd_min, but the logs always keep the same behaviour as the one shown above.

Any thought on that or any suggestion? Can I still consider the final iMPS's as reliable results, since their physical properties coincides with the ones of the finite MPS's?

Thank you to anyone that read till the end, any help would be really appreciated!

Edit: just wanted to add how I defined my model, starting from the BoseHubbardChain already implemented in the source code

Code: Select all

class BoseHubbardChain_nnn(BoseHubbardModel):

default_lattice = "Chain"
force_default_lattice = True

def init_terms(self, model_params):
# 0) Read and set parameters.
t1 = model_params.get('t1', 1.)
t2 = model_params.get('t2', 1.)
U = model_params.get('U', 0.)
V = model_params.get('V', 0)
mu = model_params.get('mu', 0)
for u in range(len(self.lat.unit_cell)):
self.add_onsite(-mu - U / 2., u, 'N')