Corner Transfer Matrix Algorithm¶
-
ctm.one_site_c4v.ctmrg_c4v.
ctm_MOVE_sl
(a, env, f_c2x2_decomp, ctm_args=<config.CTMARGS object>, global_args=<config.GLOBALARGS object>, past_steps_data=None)[source]¶ - Parameters
a (torch.Tensor) – on-site C4v symmetric tensor
env (ENV_C4V) – C4v symmetric environment
f_c2x2_decomp (function(torch.Tensor, int)->torch.Tensor, torch.Tensor) – function performing the truncated spectral decomposition (eigenvalue/svd) of enlarged corner. The
f_c2x2_decomp
returns a tuple composed of leading chi spectral values and projector on leading chi spectral values.ctm_args (CTMARGS) – CTM algorithm configuration
global_args (GLOBALARGS) – global configuration
past_steps_data – dictionary used for recording diagnostic information during CTM
Executes a single step of C4v symmetric CTM algorithm for 1-site C4v symmetric iPEPS. This variant of CTM step does not explicitly build double-layer on-site tensor.
-
ctm.one_site_c4v.ctmrg_c4v.
run
(state, env, conv_check=None, ctm_args=<config.CTMARGS object>, global_args=<config.GLOBALARGS object>)[source]¶ - Parameters
state (IPEPS_C4V) – wavefunction
env (ENV_C4V) – initial C4v symmetric environment
conv_check (function(IPEPS,ENV_C4V,Object,CTMARGS)->bool) – function which determines the convergence of CTM algorithm. If
None
, the algorithm performsctm_args.ctm_max_iter
iterations.ctm_args (CTMARGS) – CTM algorithm configuration
global_args (GLOBALARGS) – global configuration
Executes specialized CTM algorithm for 1-site C4v symmetric iPEPS starting from the intial environment
env
. To establish the convergence of CTM before the maximal number of iterations is reached aconv_check
function is invoked. Its expected signature isconv_check(IPEPS,ENV_C4V,Object,CTMARGS)
whereObject
is an arbitary argument. For example it can be a list or dict used for storing CTM data from previous steps to check convergence.If desired, CTM can be accelerated by fixed-point corner-matrix algorithm (FPCM) controlled by settings in
CTMARGS
.Note
Currently, FPCM does not support reverse-mode differentiation.