Allow to reset maximum bond dimension while changing the enviroment dim

Author: JanLuca

varipeps/peps/tensor.py

@@ -399,6 +399,7 @@ def change_chi(
         new_chi: int,
         *,
         reinitialize_env_as_identities: bool = True,
+        reset_max_chi: bool = False,
     ) -> T_PEPS_Tensor:
         """
         Change the environment bond dimension and returns new object of the class.
@@ -409,6 +410,8 @@ def change_chi(
         Keyword args:
           reinitialize_env_as_identities (:obj:`bool`):
             Reinitialize the CTM tensors as identities if decreasing the dimension.
+          reset_max_chi (:obj:`bool`):
+            Set maximal bond dimension to the same new value.
         Returns:
           :obj:`~varipeps.peps.PEPS_Tensor`:
             New instance of the class with the increased value.
@@ -418,6 +421,8 @@ def change_chi(
                 "Increase above the max value for environment bond dimension."
             )
 
+        new_max_chi = new_chi if reset_max_chi else self.max_chi
+
         if new_chi < self.chi and reinitialize_env_as_identities:
             return type(self)(
                 tensor=self.tensor,
@@ -440,7 +445,7 @@ def change_chi(
                 d=self.d,
                 D=self.D,
                 chi=new_chi,
-                max_chi=self.max_chi,
+                max_chi=new_max_chi,
             )
         else:
             return type(self)(
@@ -456,7 +461,7 @@ def change_chi(
                 d=self.d,
                 D=self.D,
                 chi=new_chi,
-                max_chi=self.max_chi,
+                max_chi=new_max_chi,
             )
 
     def increase_max_chi(

varipeps/peps/unitcell.py

@@ -450,19 +450,26 @@ def replace_unique_tensors(
             sanity_checks=False,
         )
 
-    def change_chi(self: T_PEPS_Unit_Cell, new_chi: int) -> T_PEPS_Unit_Cell:
+    def change_chi(
+        self: T_PEPS_Unit_Cell,
+        new_chi: int,
+        reset_max_chi: bool = False,
+    ) -> T_PEPS_Unit_Cell:
         """
         Change environment bond dimension of all tensors in the unit cell.
 
         Args:
           new_chi (:obj:`int`):
             New value for the environment bond dimension.
+          reset_max_chi (:obj:`bool`):
+            Set maximal bond dimension to the same new value.
         Returns:
           PEPS_Unit_Cell:
             New instance of PEPS unit cell with the new tensor list.
         """
         new_unique_tensors = type(self.data.peps_tensors)(
-            t.change_chi(new_chi) for t in self.data.peps_tensors
+            t.change_chi(new_chi, reset_max_chi=reset_max_chi)
+            for t in self.data.peps_tensors
         )
 
         new_data = self.data.replace_peps_tensors(new_unique_tensors)