Control Kept Bond Dimension in 1-Site DMRG

[cfengno1]

Hi Huanchen,

I am using 1-site DMRG but I often find that the kept bond dimension grows slowly as I increase the bond dimension.

For example, when M is increased from 20000 to 22000:

Sweep =    7 | Direction = backward | Bond dimension = 22000 | Noise =  0.00e+00 | Dav threshold =  1.00e-06
    470 GB <-- Site =  211 .. Mmps =20310 Ndav =   6 E =   -464.8258731565 Error = 6.00e-18 FLOPS = 4.44e+11 Tdav = 379.28 T = 750.85
    621 GB <-- Site =  210 .. Mmps =20559 Ndav =   9 E =   -464.8259416424 Error = 7.13e-18 FLOPS = 3.64e+11 Tdav = 639.22 T = 1049.07
    621 GB <-- Site =  209 .. Mmps =20098 Ndav =   8 E =   -464.8259783817 Error = 3.38e-18 FLOPS = 2.96e+11 Tdav = 704.36 T = 1215.37
    621 GB <-- Site =  208 .. Mmps =20392 Ndav =  10 E =   -464.8260213056 Error = 6.51e-18 FLOPS = 3.17e+11 Tdav = 789.47 T = 1182.04
    621 GB <-- Site =  207 .. Mmps =20228 Ndav =   9 E =   -464.8260713054 Error = 5.42e-18 FLOPS = 2.95e+11 Tdav = 781.31 T = 1223.11

Why this happens? How to let more states be kept?

Best,
Feng

[hczhai]

You need to add noise to allow the bond dimension to increase in a 1-site DMRG algorithm.