tidy MolecularHamiltonianMPOModel

qiskit-community · Nov 14, 2024 · debce23 · debce23
1 parent f6c7fe6
commit debce23
Showing 1 changed file with 61 additions and 60 deletions.
diff --git a/python/ffsim/tenpy/hamiltonians/molecular_hamiltonian.py b/python/ffsim/tenpy/hamiltonians/molecular_hamiltonian.py
@@ -10,6 +10,8 @@
 
 from __future__ import annotations
 
+import itertools
+
 import numpy as np
 from tenpy.models.lattice import Lattice
 from tenpy.models.model import CouplingMPOModel
@@ -56,66 +58,65 @@ def init_terms(self, params):
         )
         constant = params.get("constant", 0)
 
-        for p in range(norb):
-            for q in range(norb):
-                h1 = one_body_tensor[q, p]
-                if p == q:
-                    self.add_onsite(h1, p, "Nu")
-                    self.add_onsite(h1, p, "Nd")
-                    self.add_onsite(constant / norb, p, "Id")
-                else:
-                    self.add_coupling(h1, p, "Cdu", q, "Cu", dx0)
-                    self.add_coupling(h1, p, "Cdd", q, "Cd", dx0)
-
-                for r in range(norb):
-                    for s in range(norb):
-                        h2 = two_body_tensor[q, p, s, r]
-                        if p == q == r == s:
-                            self.add_onsite(h2 / 2, p, "Nu")
-                            self.add_onsite(-h2 / 2, p, "Nu Nu")
-                            self.add_onsite(h2 / 2, p, "Nu")
-                            self.add_onsite(-h2 / 2, p, "Cdu Cd Cdd Cu")
-                            self.add_onsite(h2 / 2, p, "Nd")
-                            self.add_onsite(-h2 / 2, p, "Cdd Cu Cdu Cd")
-                            self.add_onsite(h2 / 2, p, "Nd")
-                            self.add_onsite(-h2 / 2, p, "Nd Nd")
-                        else:
-                            self.add_multi_coupling(
-                                h2 / 2,
-                                [
-                                    ("Cdu", dx0, p),
-                                    ("Cdu", dx0, r),
-                                    ("Cu", dx0, s),
-                                    ("Cu", dx0, q),
-                                ],
-                            )
-                            self.add_multi_coupling(
-                                h2 / 2,
-                                [
-                                    ("Cdu", dx0, p),
-                                    ("Cdd", dx0, r),
-                                    ("Cd", dx0, s),
-                                    ("Cu", dx0, q),
-                                ],
-                            )
-                            self.add_multi_coupling(
-                                h2 / 2,
-                                [
-                                    ("Cdd", dx0, p),
-                                    ("Cdu", dx0, r),
-                                    ("Cu", dx0, s),
-                                    ("Cd", dx0, q),
-                                ],
-                            )
-                            self.add_multi_coupling(
-                                h2 / 2,
-                                [
-                                    ("Cdd", dx0, p),
-                                    ("Cdd", dx0, r),
-                                    ("Cd", dx0, s),
-                                    ("Cd", dx0, q),
-                                ],
-                            )
+        for p, q in itertools.product(range(norb), repeat=2):
+            h1 = one_body_tensor[q, p]
+            if p == q:
+                self.add_onsite(h1, p, "Nu")
+                self.add_onsite(h1, p, "Nd")
+                self.add_onsite(constant / norb, p, "Id")
+            else:
+                self.add_coupling(h1, p, "Cdu", q, "Cu", dx0)
+                self.add_coupling(h1, p, "Cdd", q, "Cd", dx0)
+
+            for r in range(norb):
+                for s in range(norb):
+                    h2 = two_body_tensor[q, p, s, r]
+                    if p == q == r == s:
+                        self.add_onsite(0.5 * h2, p, "Nu")
+                        self.add_onsite(-0.5 * h2, p, "Nu Nu")
+                        self.add_onsite(0.5 * h2, p, "Nu")
+                        self.add_onsite(-0.5 * h2, p, "Cdu Cd Cdd Cu")
+                        self.add_onsite(0.5 * h2, p, "Nd")
+                        self.add_onsite(-0.5 * h2, p, "Cdd Cu Cdu Cd")
+                        self.add_onsite(0.5 * h2, p, "Nd")
+                        self.add_onsite(-0.5 * h2, p, "Nd Nd")
+                    else:
+                        self.add_multi_coupling(
+                            0.5 * h2,
+                            [
+                                ("Cdu", dx0, p),
+                                ("Cdu", dx0, r),
+                                ("Cu", dx0, s),
+                                ("Cu", dx0, q),
+                            ],
+                        )
+                        self.add_multi_coupling(
+                            0.5 * h2,
+                            [
+                                ("Cdu", dx0, p),
+                                ("Cdd", dx0, r),
+                                ("Cd", dx0, s),
+                                ("Cu", dx0, q),
+                            ],
+                        )
+                        self.add_multi_coupling(
+                            0.5 * h2,
+                            [
+                                ("Cdd", dx0, p),
+                                ("Cdu", dx0, r),
+                                ("Cu", dx0, s),
+                                ("Cd", dx0, q),
+                            ],
+                        )
+                        self.add_multi_coupling(
+                            0.5 * h2,
+                            [
+                                ("Cdd", dx0, p),
+                                ("Cdd", dx0, r),
+                                ("Cd", dx0, s),
+                                ("Cd", dx0, q),
+                            ],
+                        )
 
     @staticmethod
     def from_molecular_hamiltonian(