Skip to content

Fix 2d heisenberg example and add error for bad unit cell inputs #88

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Oct 14, 2024
Merged

Fix 2d heisenberg example and add error for bad unit cell inputs #88

Show file tree
Hide file tree
Changes from 3 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
bdb140a
Fix 2d heisenberg and add warning
ryanlevy Oct 11, 2024
f75c6e8
Cleanup
ryanlevy Oct 11, 2024
1a08e32
Add yperiodic option
ryanlevy Oct 14, 2024
bbb6106
Negative sign fix
ryanlevy Oct 14, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 11 additions & 5 deletions examples/vumps/vumps_2d_heisenberg.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ conserve_qns = true
solver_tol = (x -> x / 10)
outer_iters = 10 # Number of times to increase the bond dimension
width = 4
yperiodic = false # OBC vs cylinder

##############################################################################
# CODE BELOW HERE DOES NOT NEED TO BE MODIFIED
Expand All @@ -30,24 +31,29 @@ initstate(n) = isodd(n) ? "↑" : "↓"
s = infsiteinds("S=1/2", N; conserve_qns, initstate)
ψ = InfMPS(s, initstate)

function ITensorInfiniteMPS.unit_cell_terms(::Model"heisenberg2D"; width)
function ITensorInfiniteMPS.unit_cell_terms(::Model"heisenberg2D"; width, yperiodic)
opsum = OpSum()
for i in 1:width
# Vertical
opsum += -0.5, "S+", i, "S-", mod(i + 1, width)
opsum += -0.5, "S-", i, "S+", mod(i + 1, width)
opsum += "Sz", i, "Sz", mod(i + 1, width)
opsum += -0.5, "S+", i, "S-", i + 1
opsum += -0.5, "S-", i, "S+", i + 1
opsum += "Sz", i, "Sz", i + 1
# Horizontal
opsum += -0.5, "S+", i, "S-", i + width
opsum += -0.5, "S-", i, "S+", i + width
opsum += "Sz", i, "Sz", i + width
end
if yperiodic
opsum += -0.5, "S+", 1, "S-", width
opsum += -0.5, "S-", 1, "S+", width
opsum += "Sz", 1, "Sz", width
end
return opsum
end
model = Model("heisenberg2D")

# Form the Hamiltonian
H = InfiniteSum{MPO}(model, s; width)
H = InfiniteSum{MPO}(model, s; width, yperiodic)

# Check translational invariance
# println("\nCheck translation invariance of the initial VUMPS state")
Expand Down
8 changes: 8 additions & 0 deletions src/models/models.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -245,6 +245,14 @@ function infinite_terms(opsum::OpSum; kwargs...)
# stores all terms starting on site `i`.
opsum_cell_dict = groupreduce(minimum ∘ ITensors.sites, +, opsum)
nsites = maximum(keys(opsum_cell_dict))
# check that we don't have terms we will ignore
dropped = filter(x -> x <= 0, keys(opsum_cell_dict))
if length(dropped) > 0
error(
"The input unit cell terms include terms that are being ignored on sites: $([d for d in dropped])",
)
end

# Assumes each site in the unit cell has a term
for j in 1:nsites
if !haskey(opsum_cell_dict, j)
Expand Down
Loading