[Breaking] Change the CFT data interface

docs/make.jl

@@ -10,6 +10,7 @@ makedocs(;
     pages = [
         "Home" => "index.md"
         "Library" => "lib/lib.md"
+        "CFT Data" => "cft.md"
         "Finalizers" => "finalizers.md"
         "References" => "references.md"
     ],

docs/src/cft.md

@@ -0,0 +1,32 @@
+# Conformal Field Theory Data
+TNRKit provides extensive tools for calculating conformal field theory data. Details about the implementation can be found in the TNRKit paper ([arxiv/2604.06922](https://arxiv.org/abs/2604.06922)).
+
+The core idea behind calculating the central charge, scaling dimensions, and conformal spins, is to calculate the spectrum of the fixed point tensor on a tube geometry. There are different ways to put fixed point tensors on a tube and the geometry of this tube is characterised by 3 parameters:
+$$[h, L, x]$$
+Where $h$ is the height of the tube, $L$ is the circumference, and $x$ is the horizontal shift. The higher the ratio $\frac{L}{h}$, the higher the resolution but also the more expensive the calculation.
+
+To calculate cft data we provide the `CFTData` struct which can be used in the following ways:
+
+```julia
+CFTData(scheme; shape=[h, L, x])
+CFTData(T::TensorMap; kwargs...) # 1 fixed point tensor
+CFTData(TA::TensorMap, TB::TensorMap; kwargs...) # 2x2 checkerboard unitcell
+```
+
+The shapes we provide are: $[1, 1, 0]$, $[\sqrt{2}, 2\sqrt{2}, 0]$, $[1, 4, 1]$, $[1, 8, 1]$, $[\frac{4}{\sqrt{10}}, 2 \sqrt{10}, \frac{2}{\sqrt{10}}]$
+
+The last two of which require intermediate truncation steps, the parameters of which can be tuned by:
+```julia
+CFTData(scheme; shape=[1, 8, 1], trunc = trunc1, truncentanglement=trunc2)
+```
+
+# CFTData struct
+The `CFTData` struct has two fields:
+- `central_charge`
+- `scaling_dimensions`
+
+The `central_charge` can be either `missing` (when using the $[1, 1, 0]$ shape), or a number.
+The `scaling_dimensions` field is a `SectorVector` from TensorKit.jl.
+
+The `scaling_dimensions` can be indexed like an `AbstractVector` (i.e. with scalars, slices, ...), or with sectors (e.g. `Z2Irrep(0)`), which will provide the scaling dimensions associated with that sector/charge.
+To check which sectors you can index the `scaling_dimensions` with you can use `keys(scaling_dimensions)`.

src/TNRKit.jl

@@ -120,14 +120,14 @@ include("utility/free_energy.jl")
 export free_energy
 
 include("utility/cft.jl")
-export cft_data, central_charge
+export CFTData, central_charge
 
 include("utility/gs_degeneracy.jl")
 export ground_state_degeneracy, gu_wen_ratio
 
 include("utility/finalize.jl")
 export Finalizer, two_by_two_Finalizer, finalize!, finalize_two_by_two!, finalize_cftdata!, finalize_central_charge!,
-    finalize_groundstatedegeneracy!, GSDegeneracy_Finalizer, guwenratio_Finalizer
+    finalize_groundstatedegeneracy!, CFT_Finalizer, GSDegeneracy_Finalizer, guwenratio_Finalizer
 
 include("utility/cdl.jl")
 export cdl_tensor

src/schemes/ctm/ctm_hotrg.jl

@@ -7,7 +7,7 @@ Corner Transfer Matrix environment + Higher-Order Tensor Renormalization Group
     $(FUNCTIONNAME)(T, χenv[, ctm_iter=maxiter(2.0e4), ctm_tol=trivial_convcrit(1.0e-9), ctm_obc=false, χenv_ini=2])
 
 ### Running the algorithm
-    run!(::ctm_HOTRG, trunc::TruncationStrategy, criterion::stopcrit[, sweep=30, return_cft=false, inv=false, conv_criterion=1.0e-12])
+    run!(::ctm_HOTRG, trunc::TruncationStrategy, criterion::stopcrit[, sweep=30, inv=false, conv_criterion=1.0e-12])
 
 ### Fields
 
@@ -129,29 +129,21 @@ end
 
 function run!(
         scheme::ctm_HOTRG, trunc::TruncationStrategy, criterion::stopcrit;
-        sweep = 30, return_cft = false, inv = false, conv_criterion = 1.0e-12
+        sweep = 30, inv = false, conv_criterion = 1.0e-12
     )
     area = 1
     lnz = 0.0
-    cft = []
 
     for i in 1:(criterion.n)
         area *= 4.0
         tr_norm = step!(scheme, trunc; sweep = sweep, inv = inv)
-        if return_cft
-            push!(cft, cft_data(scheme; unitcell = 2))
-        end
         lnz += log(tr_norm) / area
         if abs(log(abs(tr_norm)) / area) <= conv_criterion
             @info "CTM-HOTRG converged after $i iterations!"
             break
         end
     end
-    if return_cft
-        return lnz, cft
-    else
-        return lnz
-    end
+    return lnz
 end
 
 function Base.show(io::IO, scheme::ctm_HOTRG)

src/schemes/ctm/ctm_trg.jl

@@ -7,7 +7,7 @@ Corner Transfer Matrix environment + Tensor Renormalization Group
     $(FUNCTIONNAME)(T, χenv[, ctm_iter=2.0e4, ctm_tol=1.0e-9])
 
 ### Running the algorithm
-    run!(::ctm_TRG, trunc::TruncationStrategy, criterion::maxiter[, sweep=30, enlarge=true, return_cft=false, inv=false, conv_criterion=1.0e-12, modified=true])
+    run!(::ctm_TRG, trunc::TruncationStrategy, criterion::maxiter[, sweep=30, enlarge=true, inv=false, conv_criterion=1.0e-12, modified=true])
 
 ### Fields
 
@@ -167,36 +167,27 @@ function run!(
         criterion::maxiter;
         sweep = 30,
         enlarge = true,
-        return_cft = false,
         inv = false,
         conv_criterion = 1.0e-12,
         modified = true,
     )
     area = 1
     lnz = 0.0
-    cft = []
 
     steps = 0
     crit = true
     while crit
         area *= 4.0
         tr_norm = step!(scheme, trunc; sweep = sweep, enlarge = enlarge, inv = inv, modified)
         lnz += log(tr_norm) / area
-        if return_cft
-            push!(cft, cft_data(scheme; unitcell = 2))
-        end
         if abs(log(abs(tr_norm)) / area) <= conv_criterion
             @info "CTM-TRG converged after $steps iterations"
             break
         end
         steps += 1
         crit = criterion(steps, nothing)
     end
-    if return_cft
-        return lnz, cft
-    else
-        return lnz
-    end
+    return lnz
 end
 
 function Base.show(io::IO, scheme::ctm_TRG)