Merge pull request #2136 from mcditoos/gsocApp

added info about sec_cutoff to the documentation
qutip · Apr 11, 2023 · 4ffea33 · 4ffea33
2 parents 0801589 + 4d194ae
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diff --git a/doc/changes/2136.doc b/doc/changes/2136.doc
@@ -0,0 +1 @@
+added info about sec_cutoff to the documentation 
diff --git a/doc/guide/dynamics/dynamics-bloch-redfield.rst b/doc/guide/dynamics/dynamics-bloch-redfield.rst
@@ -283,6 +283,15 @@ The two steps of calculating the Bloch-Redfield tensor and evolving according to
 
 where the resulting `output` is an instance of the class :class:`qutip.Result`.
 
+.. note::
+    While the code example simulates the Bloch-Redfield equation in the secular approximation, QuTiP's implementation allows the user to simulate the non-secular version of the Bloch-Redfield equation by setting ``sec_cutoff=-1``, as well as do a partial secular approximation by setting it to a  ``float`` , this float will become the cutoff for the sum in :eq:`br-final` meaning terms with :math:`|\omega_{ab}-\omega_{cd}|` greater than the cutoff will be neglected.
+    Its default value is 0.1 which corresponds to the secular approximation.
+    For example the command
+    ::
+
+        output = brmesolve(H, psi0, tlist, a_ops=[[sigmax(), ohmic_spectrum]], e_ops=e_ops, sec_cutoff=-1)
+    
+    will simulate the same example as above without the secular approximation. Note that using the non-secular version may lead to negativity issues.
 
 .. _td-bloch-redfield: