Skip to content

Fixed nearest neighbor V for Kagome and add test #377

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
PDoakORNL merged 2 commits into from
Sep 25, 2026
Merged

Fixed nearest neighbor V for Kagome and add test #377

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c69092c
Corrected nearest neighbor V implementation for Kagome
maierta Sep 23, 2026
719e9c2
Merge branch 'master' of https://github.com/CompFUSE/DCA
maierta Sep 25, 2026
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: 10 additions & 6 deletions include/dca/phys/models/analytic_hamiltonians/Kagome_hubbard.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -193,14 +193,18 @@ void KagomeHubbard<PointGroupType>::initializeHInteraction(
if (r != origin) {
const int minus_r = RDmn::parameter_type::subtract(r, origin);

nn_index.push_back(r);
// H_interaction(b1, b2, delta_r) uses delta_r = R1 - R2. The orbital
// pairs below describe b1 in the reference cell and b2 in the cell at
// +nn_vec, so their displacement is -nn_vec.
nn_index.push_back(minus_r);
nn_orbs.push_back({orb_pairs[vec_idx][0], orb_pairs[vec_idx][1]});

// Add negative direction if distinct
if (r != minus_r) {
nn_index.push_back(minus_r);
nn_orbs.push_back({orb_pairs[vec_idx][1], orb_pairs[vec_idx][0]});
}
// Always add the reversed matrix element required by
// H(b1,b2,r) = H(b2,b1,-r). This is still a distinct orbital entry
// when r == -r, as happens for every nonzero displacement of the Nc=4
// cluster.
nn_index.push_back(r);
nn_orbs.push_back({orb_pairs[vec_idx][1], orb_pairs[vec_idx][0]});
}
}

Expand Down
84 changes: 53 additions & 31 deletions test/unit/phys/models/analytic_hamiltonians/kagome_hubbard_test.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include "dca/platform/dca_gpu.h"
#include "dca/phys/models/analytic_hamiltonians/bilayer_lattice.hpp"

#include <array>
#include <cmath>
#include <complex>
#include <vector>
Expand Down Expand Up @@ -109,35 +110,56 @@ TEST(KagomeLatticeTest, Initialize_H_interaction) {
else
EXPECT_DOUBLE_EQ(0., H_interaction(b1, s1, b2, s2, r));

// \todo surely the Kagome lattice has more parameters and interactions to check

// // Check nearest-neighbor opposite spin interaction.
// params.set_U(0);

// Lattice::initializeHInteraction(H_interaction, params);

// for (int r = 0; r < RClusterDmn::dmn_size(); ++r)
// for (int s2 = 0; s2 < SpinDmn::dmn_size(); ++s2)
// for (int b2 = 0; b2 < BandDmn::dmn_size(); ++b2)
// for (int s1 = 0; s1 < SpinDmn::dmn_size(); ++s1)
// for (int b1 = 0; b1 < BandDmn::dmn_size(); ++b1)
// if (std::find(nn_index.begin(), nn_index.end(), r) != nn_index.end() && s1 != s2)
// EXPECT_DOUBLE_EQ(2., H_interaction(0, s1, 0, s2, r));
// else
// EXPECT_DOUBLE_EQ(0., H_interaction(0, s1, 0, s2, r));

// Check nearest-neighbor same spin interaction.
// params.set_U(0);
// params.set_V(0);
// params.set_V_prime(1);

// Lattice::initializeHInteraction(H_interaction, params);

// for (int r = 0; r < RClusterDmn::dmn_size(); ++r)
// for (int s2 = 0; s2 < SpinDmn::dmn_size(); ++s2)
// for (int s1 = 0; s1 < SpinDmn::dmn_size(); ++s1)
// if (std::find(nn_index.begin(), nn_index.end(), r) != nn_index.end() && s1 == s2)
// EXPECT_DOUBLE_EQ(1., H_interaction(0, s1, 0, s2, r));
// else
// EXPECT_DOUBLE_EQ(0., H_interaction(0, s1, 0, s2, r));
// Check all intra-cell and intercell nearest-neighbor interactions. Every
// nonzero displacement of this Nc=4 cluster is self-inverse, so both orbital
// orderings must be present at the same real-space index.
params.set_V(2);
Lattice::initializeHInteraction(H_interaction, params);

constexpr std::array<std::array<int, 2>, 3> intra_cell_pairs = {{
{{0, 1}}, {{1, 2}}, {{0, 2}}
}};
constexpr std::array<std::array<int, 2>, 3> intercell_pairs = {{
{{2, 0}}, {{1, 2}}, {{1, 0}}
}};

auto is_pair = [](int b1, int b2, const auto& pairs) {
for (const auto& pair : pairs)
if ((b1 == pair[0] && b2 == pair[1]) ||
(b1 == pair[1] && b2 == pair[0]))
return true;
return false;
};

for (int r = 0; r < RClusterDmn::dmn_size(); ++r)
for (int s2 = 0; s2 < SpinDmn::dmn_size(); ++s2)
for (int b2 = 0; b2 < BandDmn::dmn_size(); ++b2)
for (int s1 = 0; s1 < SpinDmn::dmn_size(); ++s1)
for (int b1 = 0; b1 < BandDmn::dmn_size(); ++b1) {
double expected = 0.;
if (r == origin && b1 == b2 && s1 != s2)
expected = 4.;
else if (r == origin && is_pair(b1, b2, intra_cell_pairs))
expected = 2.;
else {
for (int direction = 0; direction < 3; ++direction)
if (r == nn_index[direction] &&
((b1 == intercell_pairs[direction][0] &&
b2 == intercell_pairs[direction][1]) ||
(b1 == intercell_pairs[direction][1] &&
b2 == intercell_pairs[direction][0])))
expected = 2.;
}
EXPECT_DOUBLE_EQ(expected, H_interaction(b1, s1, b2, s2, r));
}

for (int r = 0; r < RClusterDmn::dmn_size(); ++r) {
const int minus_r = RClusterDmn::parameter_type::subtract(r, origin);
for (int s2 = 0; s2 < SpinDmn::dmn_size(); ++s2)
for (int b2 = 0; b2 < BandDmn::dmn_size(); ++b2)
for (int s1 = 0; s1 < SpinDmn::dmn_size(); ++s1)
for (int b1 = 0; b1 < BandDmn::dmn_size(); ++b1)
EXPECT_DOUBLE_EQ(H_interaction(b1, s1, b2, s2, r),
H_interaction(b2, s2, b1, s1, minus_r));
}
}
Loading