diff --git a/src/Estimators/StructureFactorEstimator.cpp b/src/Estimators/StructureFactorEstimator.cpp
index d48fe2b86d..16a100fe4b 100644
--- a/src/Estimators/StructureFactorEstimator.cpp
+++ b/src/Estimators/StructureFactorEstimator.cpp
@@ -10,21 +10,25 @@
 //////////////////////////////////////////////////////////////////////////////////////
 
 #include "StructureFactorEstimator.h"
+#include "StructureFactorInput.h"
 #include "ParticleSet.h"
 #include <LongRange/StructFact.h>
 
 namespace qmcplusplus
 {
 
-StructureFactorEstimator::StructureFactorEstimator(StructureFactorInput& sfi,
-                                                   ParticleSet& pset_ions,
-                                                   ParticleSet& pset_elec,
+StructureFactorEstimator::StructureFactorEstimator(const StructureFactorInput& sfi,
+                                                   const ParticleSet& pset_ions,
+                                                   const ParticleSet& pset_elec,
                                                    DataLocality data_locality)
-    : OperatorEstBase(data_locality), elns_(pset_elec), ions_(pset_ions)
+    : OperatorEstBase(data_locality),
+      input_(sfi),
+      elns_(pset_elec),
+      elec_num_species_(elns_.getSpeciesSet().getTotalNum()),
+      ions_(pset_ions),
+      ion_num_species_(ions_.getSpeciesSet().getTotalNum())
 {
-  my_name_      = "StructureFactorEstimator";
-  elec_species_ = elns_.getSpeciesSet().getTotalNum();
-  ion_species_  = ions_.getSpeciesSet().getTotalNum();
+  my_name_ = "StructureFactorEstimator";
 
   num_kpoints_    = pset_ions.getSimulationCell().getKLists().numk;
   kshell_offsets_ = pset_ions.getSimulationCell().getKLists().kshell;
@@ -68,10 +72,10 @@ void StructureFactorEstimator::accumulate(const RefVector<MCPWalker>& walkers,
     //sum over species
     std::copy(psets[iw].get().getSK().rhok_r[0], psets[iw].get().getSK().rhok_r[0] + num_kpoints_, rhok_tot_r_.begin());
     std::copy(psets[iw].get().getSK().rhok_i[0], psets[iw].get().getSK().rhok_i[0] + num_kpoints_, rhok_tot_i_.begin());
-    for (int i = 1; i < elec_species_; ++i)
+    for (int i = 1; i < elec_num_species_; ++i)
       accumulate_elements(psets[iw].get().getSK().rhok_r[i], psets[iw].get().getSK().rhok_r[i] + num_kpoints_,
                           rhok_tot_r_.begin());
-    for (int i = 1; i < elec_species_; ++i)
+    for (int i = 1; i < elec_num_species_; ++i)
       accumulate_elements(psets[iw].get().getSK().rhok_i[i], psets[iw].get().getSK().rhok_i[i] + num_kpoints_,
                           rhok_tot_i_.begin());
 
diff --git a/src/Estimators/StructureFactorEstimator.h b/src/Estimators/StructureFactorEstimator.h
index f4d111f6f9..0f375fe98d 100644
--- a/src/Estimators/StructureFactorEstimator.h
+++ b/src/Estimators/StructureFactorEstimator.h
@@ -13,7 +13,6 @@
 #define QMCPLUSPLUS_STRUCTUREFACTORESTIMATOR_H
 
 #include "OperatorEstBase.h"
-#include "StructureFactorInput.h"
 
 namespace qmcplusplus
 {
@@ -23,6 +22,8 @@ namespace testing
 class StructureFactorAccess;
 }
 
+class StructureFactorInput;
+  
 class StructureFactorEstimator : public OperatorEstBase
 {
 public:
@@ -31,9 +32,9 @@ class StructureFactorEstimator : public OperatorEstBase
   using FullPrecReal = QMCT::FullPrecRealType;
   using KPt          = TinyVector<Real, QMCTraits::DIM>;
 
-  StructureFactorEstimator(StructureFactorInput& sfi,
-                           ParticleSet& pset_ions,
-                           ParticleSet& pset_elec,
+  StructureFactorEstimator(const StructureFactorInput& sfi,
+                           const ParticleSet& pset_ions,
+                           const ParticleSet& pset_elec,
                            DataLocality data_locality = DataLocality::crowd);
 
   StructureFactorEstimator(const StructureFactorEstimator& sfe, DataLocality dl);
@@ -66,11 +67,12 @@ class StructureFactorEstimator : public OperatorEstBase
 private:
   StructureFactorEstimator(const StructureFactorEstimator& obdm) = default;
 
-  int elec_species_;
-  ParticleSet& elns_;
-  int ion_species_;
-  ParticleSet& ions_;
-
+  const StructureFactorInput& input_;
+  const ParticleSet& elns_;
+  const int elec_num_species_;
+  const ParticleSet& ions_;
+  const int ion_num_species_;
+  
   /// number of k points
   long long num_kpoints_;
 
diff --git a/src/Estimators/tests/GenerateRandomParticleSets.cpp b/src/Estimators/tests/GenerateRandomParticleSets.cpp
index 0c3051e7dd..95b9e102c0 100644
--- a/src/Estimators/tests/GenerateRandomParticleSets.cpp
+++ b/src/Estimators/tests/GenerateRandomParticleSets.cpp
@@ -32,7 +32,7 @@ std::vector<ParticleSet> generateRandomParticleSets(ParticleSet& pset_target,
   std::vector<ParticleSet> psets(num_psets, pset_target);
   if (generate_test_data)
   {
-    std::cout << "Initialize psets with:\n{";
+    std::cout << "Initialize ParticleSets with:\n{";
     std::vector<ParticleSet> psets;
     for (int iw = 0; iw < nwalkers; ++iw)
     {
diff --git a/src/Estimators/tests/test_StructureFactorEstimator.cpp b/src/Estimators/tests/test_StructureFactorEstimator.cpp
index 94d3fec5c3..dee50bfd5a 100644
--- a/src/Estimators/tests/test_StructureFactorEstimator.cpp
+++ b/src/Estimators/tests/test_StructureFactorEstimator.cpp
@@ -12,6 +12,7 @@
 #include "catch.hpp"
 
 #include "StructureFactorEstimator.h"
+#include "StructureFactorInput.h"
 #include "ValidStructureFactorInput.h"
 #include "Particle/tests/MinimalParticlePool.h"
 #include "QMCWaveFunctions/tests/MinimalWaveFunctionPool.h"
diff --git a/src/type_traits/tests/test_template_types.cpp b/src/type_traits/tests/test_template_types.cpp
index f8cb0c2a0a..49fecf0e3e 100644
--- a/src/type_traits/tests/test_template_types.cpp
+++ b/src/type_traits/tests/test_template_types.cpp
@@ -2,7 +2,7 @@
 // This file is distributed under the University of Illinois/NCSA Open Source License.
 // See LICENSE file in top directory for details.
 //
-// Copyright (c) 2019 QMCPACK developers
+// Copyright (c) 2024 QMCPACK developers
 //
 // File developed by: Peter Doak, doakpw@ornl.gov, Oak Ridge National Lab
 //
@@ -79,8 +79,6 @@ TEST_CASE("convertUPtrToRefvector", "[type_traits]")
 
   // This should cause a compilation error. a DerivedDummy cannot be converted to an OtherDummy.
   // RefVector<OtherDummy> od_ref_vec = convertUPtrToRefVector<OtherDummy>(ddv);
-
-  
 }
 
 TEST_CASE("convertPtrToRefvectorSubset", "[type_traits]")