#!/bin/bash

# Check the existence of a test version of the mdgx program
MDGX="${AMBERHOME}/bin/mdgx"
if [ -n "${TESTmdgx}" ] ; then
  MDGX=${TESTmdgx}
  echo "MDGX set to ${MDGX}"
fi

# Write a simple input file
cat > mdgx.in << EOF
&files
  -p       ../NVTwat/wat.top    % Use the topology and initial 
  -c       ../NVTwat/wat.rst    % coordinates from the NVTwat test
  -xpt     wat4.xpt             % This file modifies TIP3P to become TIP4P
  -r       wat
  -o       wat
  -x       wat
  -f       wat
  -osf     .out
  -rsf     .rst
  -xsf     .trj
  -fsf     .frc
&end

&cntrl

  % Settle is active to keep the water rigid
  DoSETTLE = 1,     DoRATTLE = 0,

  % Scaling for 1:4 nonbonded interactions
  Vdw14Fac = 2.0,   Elec14Fac = 1.2,

  % Direct-space cutoff
  cut = 8.000,

  % 1fs time step
  dt = 1.0e-3,

  % Run for 40 steps in all
  nstlim = 40,  nfistep = 0,
  ntpr = 5,     ntwr = 40,     
  ntwf = 0,     ntwx = 0,

  % Berendsen barostat
  ntt  = 1,        tempi = 300.0,   temp0 = 300.0,

  % Higher accuracy in the direct-space lookup table
  SplnSpc = 0.015625,

  % Constant-pressure dynamics maintained by a Monte-Carlo barostat
  ntp     = 1,     barostat = 2,     mcbfrq  = 10,
  mcbtemp = 300.0, mccomp  = 2.0e-3,
&end

&ewald
  vdwmeth = 1,
  dsum_tol = 1.0e-5,
  ordr1 = 4,
  ordr2 = 4,
  ordr3 = 4,
&end
EOF

# Run the mdgx program
${MDGX} -O -i mdgx.in

# Analyze the relevant output
echo "% Total energy" > etot.dat
grep "^ Etot:" wat.out >> etot.dat

${AMBERHOME}/AmberTools/test/dacdif etot.dat.save etot.dat
/bin/rm -f mdgx.in wat.rst wat.out