diff --git a/CMakeLists.txt b/CMakeLists.txt
index 02df7cb732..11a020e53f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -388,7 +388,7 @@ set(SeQuant_src
         SeQuant/domain/mbpt/spin.cpp
         SeQuant/domain/mbpt/spin.hpp
         SeQuant/domain/mbpt/vac_av.hpp
-        SeQuant/domain/mbpt/vac_av.ipp
+        SeQuant/domain/mbpt/vac_av.cpp
         SeQuant/domain/mbpt/utils.hpp
         SeQuant/domain/mbpt/utils.cpp
         SeQuant/version.cpp
diff --git a/SeQuant/domain/mbpt/models/cc.hpp b/SeQuant/domain/mbpt/models/cc.hpp
index 0759d60f2b..5753428c88 100644
--- a/SeQuant/domain/mbpt/models/cc.hpp
+++ b/SeQuant/domain/mbpt/models/cc.hpp
@@ -3,6 +3,7 @@
 
 #include <SeQuant/core/op.hpp>
 #include <SeQuant/domain/mbpt/op.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 #include <cstddef>
 #include <limits>
diff --git a/SeQuant/domain/mbpt/op.cpp b/SeQuant/domain/mbpt/op.cpp
index b2f87195e9..adde256dc1 100644
--- a/SeQuant/domain/mbpt/op.cpp
+++ b/SeQuant/domain/mbpt/op.cpp
@@ -1236,13 +1236,11 @@ bool lowers_rank_to_vacuum(const ExprPtr& op_or_op_product,
   return can_change_qns(op_or_op_product, qns_t{}, excitation_type_qns(k));
 }
 
-#include <SeQuant/domain/mbpt/vac_av.ipp>
-
 namespace tensor {
 
-ExprPtr detail::expectation_value_impl(
-    ExprPtr expr, std::vector<std::pair<int, int>> nop_connections,
-    bool use_top, bool full_contractions) {
+ExprPtr expectation_value_impl(ExprPtr expr,
+                               std::vector<std::pair<int, int>> nop_connections,
+                               bool use_top, bool full_contractions) {
   simplify(expr);
   auto isr = get_default_context().index_space_registry();
   const auto spinor = get_default_context().spbasis() == SPBasis::Spinor;
@@ -1466,38 +1464,17 @@ ExprPtr ref_av(ExprPtr expr, std::vector<std::pair<int, int>> nop_connections,
   const bool full_contractions =
       (isr->reference_occupied_space() == isr->vacuum_occupied_space()) ? true
                                                                         : false;
-  return detail::expectation_value_impl(expr, nop_connections, use_top,
-                                        full_contractions);
+  return expectation_value_impl(expr, nop_connections, use_top,
+                                full_contractions);
 }
 
 ExprPtr vac_av(ExprPtr expr, std::vector<std::pair<int, int>> nop_connections,
                bool use_top) {
-  return detail::expectation_value_impl(expr, nop_connections, use_top,
-                                        /* full_contractions*/ true);
+  return expectation_value_impl(expr, nop_connections, use_top,
+                                /* full_contractions*/ true);
 }
 
 }  // namespace tensor
 }  // namespace op
 
-bool can_change_qns(const ExprPtr& op_or_op_product, const qns_t target_qns,
-                    const qns_t source_qns = {}) {
-  qns_t qns = source_qns;
-  if (op_or_op_product.is<Product>()) {
-    const auto& op_product = op_or_op_product.as<Product>();
-    for (auto& op_ptr : ranges::views::reverse(op_product.factors())) {
-      SEQUANT_ASSERT(op_ptr->template is<op_t>());
-      const auto& op = op_ptr->template as<op_t>();
-      qns = op(qns);
-    }
-    return qns.overlaps_with(target_qns);
-  } else if (op_or_op_product.is<op_t>()) {
-    const auto& op = op_or_op_product.as<op_t>();
-    qns = op(qns);
-    return qns.overlaps_with(target_qns);
-  } else
-    throw std::invalid_argument(
-        "sequant::mbpt::sr::contains_rank(op_or_op_product): op_or_op_product "
-        "must be mbpt::sr::op_t or Product thereof");
-}
-
 }  // namespace sequant::mbpt
diff --git a/SeQuant/domain/mbpt/op.hpp b/SeQuant/domain/mbpt/op.hpp
index 64f597ddc2..f980e5f321 100644
--- a/SeQuant/domain/mbpt/op.hpp
+++ b/SeQuant/domain/mbpt/op.hpp
@@ -555,11 +555,9 @@ qns_t generic_deexcitation_qns(std::size_t particle_rank, std::size_t hole_rank,
 
 inline namespace op {
 namespace tensor {
-namespace detail {
 ExprPtr expectation_value_impl(ExprPtr expr,
                                std::vector<std::pair<int, int>> nop_connections,
                                bool use_top, bool full_contractions);
-}  // namespace detail
 
 /// @brief computes the reference expectation value of a tensor-level expression
 /// @param expr input expression
@@ -1304,7 +1302,6 @@ bool raises_vacuum_to_rank(const ExprPtr& op_or_op_product,
 bool lowers_rank_to_vacuum(const ExprPtr& op_or_op_product,
                            const unsigned long k);
 
-#include <SeQuant/domain/mbpt/vac_av.hpp>
 }  // namespace op
 }  // namespace mbpt
 }  // namespace sequant
diff --git a/SeQuant/domain/mbpt/vac_av.ipp b/SeQuant/domain/mbpt/vac_av.cpp
similarity index 84%
rename from SeQuant/domain/mbpt/vac_av.ipp
rename to SeQuant/domain/mbpt/vac_av.cpp
index 79cedd0e0c..f9aba37bf1 100644
--- a/SeQuant/domain/mbpt/vac_av.ipp
+++ b/SeQuant/domain/mbpt/vac_av.cpp
@@ -2,12 +2,24 @@
 // Created by Eduard Valeyev on 8/2/23.
 //
 
-//  operator-level vac_av is same for SR and MR, to be included from {sr,mr}.cpp
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
-#ifndef SEQUANT_DOMAIN_MBPT_VAC_AV_IPP
-#define SEQUANT_DOMAIN_MBPT_VAC_AV_IPP
+#include <SeQuant/core/context.hpp>
+#include <SeQuant/core/expr.hpp>
+#include <SeQuant/core/op.hpp>
+#include <SeQuant/core/utility/macros.hpp>
+
+#include <range/v3/algorithm/any_of.hpp>
+#include <range/v3/algorithm/for_each.hpp>
+#include <range/v3/range/conversion.hpp>
+#include <range/v3/view/filter.hpp>
+
+#include <vector>
+
+namespace sequant {
+namespace mbpt {
+inline namespace op {
 
-namespace detail {
 ExprPtr expectation_value_impl(
     ExprPtr expr, const OpConnections<std::wstring>& op_connections,
     bool use_topology, bool screen, bool skip_clone, bool full_contractions) {
@@ -90,8 +102,8 @@ ExprPtr expectation_value_impl(
 
     // compute expectation value
     // call the tensor-level impl function directly
-    auto vev = tensor::detail::expectation_value_impl(
-        product, connections, use_topology, full_contractions);
+    auto vev = tensor::expectation_value_impl(product, connections,
+                                              use_topology, full_contractions);
     // restore Variable types to the Product
     if (!variables.empty())
       ranges::for_each(variables, [&vev](const auto& var) { vev *= var; });
@@ -128,9 +140,9 @@ ExprPtr expectation_value_impl(
     return expr;  // vacuum is normalized
   }
   throw std::invalid_argument(
-      "mpbt::*::expectation_value_impl(expr): unknown expression type");
+      "mbpt::op::detail::expectation_value_impl(expr): unknown expression "
+      "type");
 }
-}  // namespace detail
 
 ExprPtr ref_av(ExprPtr expr, const OpConnections<std::wstring>& op_connections,
                bool use_topology, bool screen, bool skip_clone) {
@@ -138,8 +150,8 @@ ExprPtr ref_av(ExprPtr expr, const OpConnections<std::wstring>& op_connections,
   const bool full_contractions =
       (isr->reference_occupied_space() == isr->vacuum_occupied_space()) ? true
                                                                         : false;
-  return detail::expectation_value_impl(expr, op_connections, use_topology,
-                                        screen, skip_clone, full_contractions);
+  return expectation_value_impl(expr, op_connections, use_topology, screen,
+                                skip_clone, full_contractions);
 }
 
 ExprPtr ref_av(ExprPtr expr, const OpConnections<OpType>& op_connections,
@@ -150,9 +162,9 @@ ExprPtr ref_av(ExprPtr expr, const OpConnections<OpType>& op_connections,
 
 ExprPtr vac_av(ExprPtr expr, const OpConnections<std::wstring>& op_connections,
                bool use_topology, bool screen, bool skip_clone) {
-  return detail::expectation_value_impl(expr, op_connections, use_topology,
-                                        screen, skip_clone,
-                                        /* full_contractions*/ true);
+  return expectation_value_impl(expr, op_connections, use_topology, screen,
+                                skip_clone,
+                                /* full_contractions */ true);
 }
 
 ExprPtr vac_av(ExprPtr expr, const OpConnections<OpType>& op_connections,
@@ -161,4 +173,6 @@ ExprPtr vac_av(ExprPtr expr, const OpConnections<OpType>& op_connections,
                 screen, skip_clone);
 }
 
-#endif  // SEQUANT_DOMAIN_MBPT_VAC_AV_IPP
+}  // namespace op
+}  // namespace mbpt
+}  // namespace sequant
diff --git a/SeQuant/domain/mbpt/vac_av.hpp b/SeQuant/domain/mbpt/vac_av.hpp
index 99e70a666b..4830f219d6 100644
--- a/SeQuant/domain/mbpt/vac_av.hpp
+++ b/SeQuant/domain/mbpt/vac_av.hpp
@@ -2,6 +2,14 @@
 // Created by Eduard Valeyev on 2023-10-30.
 //
 
+#ifndef SEQUANT_DOMAIN_MBPT_VAC_AV_HPP
+#define SEQUANT_DOMAIN_MBPT_VAC_AV_HPP
+
+#include <SeQuant/domain/mbpt/op.hpp>
+
+namespace sequant::mbpt {
+inline namespace op {
+
 template <typename T>
 using OpConnections = std::vector<std::pair<T, T>>;
 
@@ -73,13 +81,10 @@ inline ExprPtr lower_to_tensor_form(const ExprPtr& expr_inp) {
   return expr;
 }
 
-namespace detail {
 ExprPtr expectation_value_impl(
     ExprPtr expr, const OpConnections<std::wstring>& op_connections,
     bool use_topology, bool screen, bool skip_clone, bool full_contractions);
 
-}  // namespace detail
-
 // clang-format off
 /// @brief computes the reference expectation value
 /// @note equivalent to vac_av if the reference state is the Wick vacuum,
@@ -165,3 +170,7 @@ ExprPtr vac_av(ExprPtr expr,
                    default_op_connections(),
                bool use_topology = true, bool screen = true,
                bool skip_clone = false);
+
+}  // namespace op
+}  // namespace sequant::mbpt
+#endif  // SEQUANT_DOMAIN_MBPT_VAC_AV_HPP
diff --git a/doc/examples/synopsis/synopsis6.cpp b/doc/examples/synopsis/synopsis6.cpp
index 2c1817ca5d..82a1b51101 100644
--- a/doc/examples/synopsis/synopsis6.cpp
+++ b/doc/examples/synopsis/synopsis6.cpp
@@ -3,6 +3,7 @@
 #include <SeQuant/core/op.hpp>
 #include <SeQuant/domain/mbpt/convention.hpp>
 #include <SeQuant/domain/mbpt/op.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 inline auto commutator(auto op1, auto op2) { return op1 * op2 - op2 * op1; }
 
diff --git a/doc/examples/user/getting_started/ccd.cpp b/doc/examples/user/getting_started/ccd.cpp
index e83bcb350b..ea65012454 100644
--- a/doc/examples/user/getting_started/ccd.cpp
+++ b/doc/examples/user/getting_started/ccd.cpp
@@ -3,6 +3,7 @@
 #include <SeQuant/core/op.hpp>
 #include <SeQuant/domain/mbpt/convention.hpp>
 #include <SeQuant/domain/mbpt/op.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 inline auto commutator(auto op1, auto op2) { return op1 * op2 - op2 * op1; }
 
diff --git a/doc/examples/user/operator.cpp b/doc/examples/user/operator.cpp
index 4c487d7945..ba7f952fdb 100644
--- a/doc/examples/user/operator.cpp
+++ b/doc/examples/user/operator.cpp
@@ -6,6 +6,7 @@
 #include <SeQuant/core/expr.hpp>
 #include <SeQuant/domain/mbpt/convention.hpp>
 #include <SeQuant/domain/mbpt/op.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 int main() {
   // start-snippet-0
diff --git a/python/src/sequant/mbpt.h b/python/src/sequant/mbpt.h
index a027c75e84..e326c78e9d 100644
--- a/python/src/sequant/mbpt.h
+++ b/python/src/sequant/mbpt.h
@@ -3,6 +3,7 @@
 
 #include <SeQuant/domain/mbpt/convention.hpp>
 #include <SeQuant/domain/mbpt/op.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 #include <SeQuant/core/expr.hpp>
 #include <SeQuant/core/tensor_canonicalizer.hpp>
diff --git a/tests/unit/test_mbpt.cpp b/tests/unit/test_mbpt.cpp
index 828247c06b..abd260e615 100644
--- a/tests/unit/test_mbpt.cpp
+++ b/tests/unit/test_mbpt.cpp
@@ -17,6 +17,7 @@
 #include <SeQuant/domain/mbpt/rules/df.hpp>
 #include <SeQuant/domain/mbpt/rules/thc.hpp>
 #include <SeQuant/domain/mbpt/utils.hpp>
+#include <SeQuant/domain/mbpt/vac_av.hpp>
 
 #include <catch2/catch_test_macros.hpp>
 #include <catch2/matchers/catch_matchers.hpp>