diff --git a/HMC/site_autocorrelation.cc b/HMC/site_autocorrelation.cc
new file mode 100644
index 00000000..d1d1b98e
--- /dev/null
+++ b/HMC/site_autocorrelation.cc
@@ -0,0 +1,90 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: 
+
+Copyright (C) 2017
+
+Author: Peter Boyle
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+See the full license in the file "LICENSE" in the top level distribution
+directory
+*************************************************************************************/
+/*  END LEGAL */
+#include <Grid/Grid.h>
+#include <string>
+
+template <class T> void readFile(T& out, std::string const fname){
+  Grid::emptyUserRecord record;
+  Grid::ScidacReader RD;
+  RD.open(fname);
+  RD.readScidacFieldRecord(out,record);
+  RD.close();
+}
+
+
+int main(int argc, char **argv) {
+  using namespace Grid;
+  
+  Grid_init(&argc, &argv);
+  GridLogLayout();
+
+  auto latt_size   = GridDefaultLatt();
+  auto simd_layout = GridDefaultSimd(Nd, vComplex::Nsimd());
+  auto mpi_layout  = GridDefaultMpi();
+  GridCartesian               Grid(latt_size, simd_layout, mpi_layout);
+
+  LatticeComplexD plaq1(&Grid), plaq2(&Grid);
+
+  FieldMetaData header;
+
+  double vol = plaq1.Grid()->gSites();
+  
+  std::string file1(argv[1]);
+  std::cout << "Reading "<<file1<<std::endl;
+  readFile(plaq1,file1);
+  std::string file2(argv[2]);
+  std::cout << "Reading "<<file2<<std::endl;
+  readFile(plaq2,file2);
+  
+  auto p1bar = TensorRemove(sum(plaq1));
+  auto p2bar = TensorRemove(sum(plaq2));
+
+  p1bar = p1bar / vol;
+  p2bar = p2bar / vol;
+
+  std::cout<< GridLogMessage << "p1bar = "<<p1bar<<std::endl;
+  std::cout<< GridLogMessage << "p2bar = "<<p2bar<<std::endl;
+
+  auto corr_site = plaq1 * plaq2 - p1bar * p2bar;
+  auto corr_bar  = TensorRemove(sum(corr_site))/vol;
+
+  auto cov1_site = plaq1 * plaq1 - p1bar * p1bar;
+  auto cov1_bar  = TensorRemove(sum(cov1_site))/vol;
+
+  auto cov2_site = plaq2 * plaq2 - p2bar * p2bar;
+  auto cov2_bar  = TensorRemove(sum(cov2_site))/vol;
+
+  std::cout<< GridLogMessage << "cov_bar = "<<corr_bar<<std::endl;
+
+  std::cout<< GridLogMessage << "corr_bar = "<<corr_bar/sqrt(cov1_bar*cov2_bar)<<std::endl;
+  
+  Grid_finalize();
+}  // main
+
+
diff --git a/HMC/site_plaquette.cc b/HMC/site_plaquette.cc
new file mode 100644
index 00000000..2b98b5d1
--- /dev/null
+++ b/HMC/site_plaquette.cc
@@ -0,0 +1,79 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: 
+
+Copyright (C) 2017
+
+Author: Peter Boyle
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+See the full license in the file "LICENSE" in the top level distribution
+directory
+*************************************************************************************/
+/*  END LEGAL */
+#include <Grid/Grid.h>
+#include <string>
+
+NAMESPACE_BEGIN(Grid);
+template <class T> void writeFile(T& out, std::string const fname){
+  emptyUserRecord record;
+  ScidacWriter WR(out.Grid()->IsBoss());
+  WR.open(fname);
+  WR.writeScidacFieldRecord(out,record,0,Grid::BinaryIO::BINARYIO_LEXICOGRAPHIC);
+  WR.close();
+}
+NAMESPACE_END(Grid);
+int main(int argc, char **argv) {
+  using namespace Grid;
+  
+  Grid_init(&argc, &argv);
+  GridLogLayout();
+
+  auto latt_size   = GridDefaultLatt();
+  auto simd_layout = GridDefaultSimd(Nd, vComplex::Nsimd());
+  auto mpi_layout  = GridDefaultMpi();
+  GridCartesian               Grid(latt_size, simd_layout, mpi_layout);
+
+  LatticeGaugeField Umu(&Grid);
+  std::vector<LatticeColourMatrix> U(4,&Grid);
+  LatticeComplexD plaq(&Grid);
+
+  FieldMetaData header;
+
+  double vol = Umu.Grid()->gSites();
+  double faces = (1.0 * Nd * (Nd - 1)) / 2.0;
+  double Ncdiv = 1.0/Nc;
+  
+  std::string file1(argv[1]);
+  std::string file2(argv[2]);
+  std::cout << "Reading "<<file1<<std::endl;
+  NerscIO::readConfiguration(Umu,header,file1);
+  for(int mu=0;mu<Nd;mu++){
+    U[mu] = PeekIndex<LorentzIndex>(Umu,mu);
+  }
+  SU3WilsonLoops::sitePlaquette(plaq,U);
+
+  plaq = plaq *(Ncdiv/faces);
+  
+  std::cout << "Writing "<<file2<<std::endl;
+  writeFile(plaq,file2);
+  
+  Grid_finalize();
+}  // main
+
+