[tet.py] Update the singlet and triplet in Parity_Hubbard.

The results of singlet and triplet does not change. But the previous
code follow the different site-index scheme than CSCS operators. So
update it to keep the consistency of the code.

tetragono/tetragono/common_tensor/Parity_Hubbard.py

@@ -41,15 +41,15 @@
     rename_io(CP2, [0, 3]),
     rename_io(I, [1]),
     rename_io(I, [2]),
-) - kronecker_product(
+) + kronecker_product(
     rename_io(CP2, [1, 2]),
     rename_io(I, [0]),
     rename_io(I, [3]),
 ) + kronecker_product(
     rename_io(CM2, [3, 0]),
     rename_io(I, [1]),
     rename_io(I, [2]),
-) - kronecker_product(
+) + kronecker_product(
     rename_io(CM2, [2, 1]),
     rename_io(I, [0]),
     rename_io(I, [3]),
@@ -58,15 +58,15 @@
     rename_io(CP2, [0, 3]),
     rename_io(I, [1]),
     rename_io(I, [2]),
-) + kronecker_product(
+) - kronecker_product(
     rename_io(CP2, [1, 2]),
     rename_io(I, [0]),
     rename_io(I, [3]),
 ) + kronecker_product(
     rename_io(CM2, [3, 0]),
     rename_io(I, [1]),
     rename_io(I, [2]),
-) + kronecker_product(
+) - kronecker_product(
     rename_io(CM2, [2, 1]),
     rename_io(I, [0]),
     rename_io(I, [3]),
@@ -79,16 +79,16 @@
     "O1": ["O1", "O3"],
 }, put_sign_in_H, {"O0", "O1"})
 singlet = singlet.merge_edge({
-    "I0": ["I0", "I1"],
-    "O0": ["O0", "O1"],
-    "I1": ["I2", "I3"],
-    "O1": ["O2", "O3"],
+    "I0": ["I0", "I2"],
+    "O0": ["O0", "O2"],
+    "I1": ["I1", "I3"],
+    "O1": ["O1", "O3"],
 }, put_sign_in_H, {"O0", "O1"})
 triplet = triplet.merge_edge({
-    "I0": ["I0", "I1"],
-    "O0": ["O0", "O1"],
-    "I1": ["I2", "I3"],
-    "O1": ["O2", "O3"],
+    "I0": ["I0", "I2"],
+    "O0": ["O0", "O2"],
+    "I1": ["I1", "I3"],
+    "O1": ["O1", "O3"],
 }, put_sign_in_H, {"O0", "O1"})
 
 NN = kronecker_product(rename_io(N, [0]), rename_io(N, [1]))