basic_dmrg.py File Reference

Basic DMRG implementationDo not use this for actual calculations, only for illustrative purposes! More...

Detailed Description

Basic DMRG implementation

Do not use this for actual calculations, only for illustrative purposes!

Tasks:

1) add the definitions of the currently-missing contractions and energy calculation until no more NotImplementedError exceptions are thrown.

2) try to increase the bond dimension to get a more accuracte result (smaller variance)

3) enable subspace expansion by setting do_expansion to True and implement it for the right-to-left direction

4) re-run and approx. mark down the bond dimension necessary to achieve a given variance (e.g. variance 1e-5, 1e-7, 1e-10, 1e-12).

5) answer 'n' at the end and calculate the variance of the state with 'syten-expectation': $ syten-expectation groundstate-nil.mps spinchain-nil.lat:H

6) set the 'symmetry' variable to 'u1' and repeat steps 4 and Note a decreased runtime and smaller file size

7) set the 'symmetry' variable to 'su2' and repeat steps 4 and Note the smaller bond dimensions necessary with SU(2) symmetry.