qmcpack/tests/molecules/CHN_ae/qmc-ref

#HCN test targets essentially the Cusp Correction algorithm for all electron calculations.

A run will triger the generation of the Cusp Correction parameters as shown in files downdet.cuspInfo.xml  updet.cuspInfo.xml

the VMC energy is then computed to evaluate the local energy and variance.
The long VMC reference run used to extrapolate the short run reference used the following VMC blocks:

  <qmc method="vmc" move="pbyp" checkpoint="-1">
    <estimator name="LocalEnergy" hdf5="no"/>
    <parameter name="samplesperthread">1</parameter>
    <parameter name="stepsbetweensamples">100</parameter>
    <parameter name="substeps">5</parameter>
    <parameter name="warmupSteps">20</parameter>
    <parameter name="blocks">655000</parameter>
    <parameter name="timestep">0.5</parameter>
    <parameter name="usedrift">no</parameter>
  </qmc>


This leads to the following statistics:

frag00005_B3LYP  series 0 
  LocalEnergy           =         -93.33930 +/-          0.00027 
  Variance              =             2.381 +/-            0.010 
  Kinetic               =            93.249 +/-            0.047 
  LocalPotential        =          -186.588 +/-            0.047 
  ElecElec              =           55.2886 +/-           0.0013 
  IonIon                =             24.03 +/-             0.00 
  IonElec               =          -265.910 +/-            0.047 
  LocalEnergy_sq        =          8714.606 +/-            0.051 
  BlockWeight           =           4096.00 +/-             0.00 
  BlockCPU              =       0.010012609 +/-      0.000000060 
  AcceptRatio           =         0.3281958 +/-        0.0000037 
  Efficiency            =          18549.36 +/-             0.00 
  TotalTime             =            654.39 +/-             0.00 
  TotalSamples          =         267702272 +/-                0

However, In order to keep the size of the files small in the reference directory, an equivalent VMC block was used using 1 sample per thread and 4096 threads

  <qmc method="vmc" move="pbyp" checkpoint="-1">
    <estimator name="LocalEnergy" hdf5="no"/>
    <parameter name="samplesperthread">1</parameter>
    <parameter name="stepsbetweensamples">100000</parameter>
    <parameter name="substeps">5</parameter>
    <parameter name="warmupSteps">20</parameter>
    <parameter name="blocks">200</parameter>
    <parameter name="timestep">0.5</parameter>
    <parameter name="usedrift">no</parameter>
  </qmc>


This leads to the following statistics:

vmc-ref  series 0 
  LocalEnergy           =         -93.33934 +/-          0.00021 
  Variance              =            2.3797 +/-           0.0043 
  Kinetic               =            93.179 +/-            0.045 
  LocalPotential        =          -186.518 +/-            0.045 
  ElecElec              =           55.2876 +/-           0.0013 
  IonIon                =             24.03 +/-             0.00 
  IonElec               =          -265.839 +/-            0.045 
  LocalEnergy_sq        =          8714.613 +/-            0.040 
  BlockWeight           =        2048000.00 +/-             0.00 
  BlockCPU              =          5.017721 +/-         0.000024 
  AcceptRatio           =         0.3282004 +/-        0.0000033 
  Efficiency            =             37.90 +/-             0.00 
  TotalTime             =           1003.54 +/-             0.00 
  TotalSamples          =         409600000 +/-                0