waterSphere

#!@PERL_EXECUTABLE@
 
# program that builds spheres of water
 
# author    = "Dan Gezelter
# copyright = "Copyright (c) 2004-present The University of Notre Dame. All Rights Reserved."
# license   = "OpenMD"
 
use Getopt::Std;
use List::Util qw[min max];
 
 
$tolerance = 1.0E-8;
$mass = 2.99151E-23; # mass of H2O in grams
$cm3ToAng3 = 1E24;   # convert cm^3 to angstroms^3
$densityConvert = $mass*$cm3ToAng3;
$lattice = 0;
$density = 1.0;
$doRandomize = 0;
$cutoff = 9;
$rcut = 3.2;
$alpha = 0.18;
$invalidWater = 0;
$waterCase = -1;
$nothingSelected = 1;
 
# get our options
getopts('hmrvd:l:c:o:w:O:I:');
 
# just to test opt_h
$opt_h = "true" if $#ARGV >= 0;
 
# our option output
if ($opt_h){
    print "waterSphere: builds spheres of water\n\n";
    print "usage: waterSphere [-hmrv] [-d density] [-l lattice] [-n # waters]\n";
    print "\t[-o file name] [-w water name] \n\n";
    print "  -h : show this message\n";
    print "  -m : print out a water.inc file (file with all water models)\n";
    print "  -r : randomize orientations\n";
    print "  -v : verbose output\n\n";
    print "  -d real    : density in g/cm^3\n";
    print "                 (default: 1)\n";
    print "  -l integer : 0 - face centered cubic, 1 - simple cubic\n";
    print "                 (default: 0)\n";
 
 
    print "  -c real    : default overlap cutoff in angstroms\n";
    print "                 (default: 3.3)\n";
    print "  -o char    : output file name\n";
    print "                 (default: freshWater.omd)\n";
    print "  -w char    : name of the water stunt double\n";
    print "                 (default: SPCE)\n";
    print "  -R real    : outer radius of the water sphere\n";
    print "  -I real    : inner radius of the water sphere\n";
    print "Note: you can only use values of -O that are smaller\n";
    print "      than the derived radius for a given density and\n";
    print "      number of molecules.\n\n";
    print "Example:\n";
    die   "   waterSphere -d 0.997 -I 20 -O 40 -w SSD_RF -o ssdrfWater.omd\n";
}
 
# set some variables to be used in the code
if (defined($opt_o)){
  $fileName = $opt_o;
  $nothingSelected = 0;
} else {
    $fileName = 'freshWater.omd';
}
if ($opt_m){
  die "Error: $fileName cannot be \"water.inc\"\n       Please choose a different name\n" if $fileName eq 'water.inc';
  $waterFileHandle = 'WATERMD';
  $nothingSelected = 0;
} else {
  $waterFileHandle = 'OUTFILE';
}
if ($opt_r){
  $doRandomize = $opt_r;
  $nothingSelected = 0;
}
 
if (defined($opt_d)){
  $nothingSelected = 0;
  if ($opt_d =~ /^[0-9]/) {
    $density = $opt_d;
  } else {
    die "Error: the value for '-d' ($opt_d) is not a valid number\n       Please choose a positive real # value\n";
  }
}
if (defined($opt_c)){
  $nothingSelected = 0;
  if ($opt_c =~ /^[0-9]/) {
    $rcut = $opt_c;
  } else {
    die "Error: the value for '-c' ($opt_c) is not a valid number\n       Please choose a positive real # value\n";
  }
}
 
if (defined($opt_w)){
  $waterName = $opt_w;
  $nothingSelected = 0;
} else {
  $waterName = 'SPCE';
}
validateWater();
if ($invalidWater == 1){
  print "Warning: \'$waterName\' is not a recognized water model name.\n";
  print "         Use the \'-m\' option to generate a \'water.inc\' with the\n";
  print "         recognized water model geometries.\n\n";
}
if ($waterName eq 'DPD') {
  # DPD waters are stand-ins for 4 water molecules
  $density = $density * 0.25;
}
if ($waterName eq 'CG2') {
  # CG2 waters are stand-ins for 2 water molecules
  $density = $density * 0.5;
}
 
if (defined($opt_l)){
  $nothingSelected = 0;
  if ($opt_l =~ /^[0-9]/) {
    $lattice = $opt_l;
    if ($lattice != 0 && $lattice != 1){
      die "Error: the '-l' value ($opt_l) is not a valid number\n       Please choose 0 or 1\n";
    }
  } else {
    die "Error: the '-l' value ($opt_l) is not a valid number\n       Please choose 0 or 1\n";
  }
}
if (defined($opt_O)){
  $nothingSelected = 0;
  if ($opt_O =~ /^[0-9]/) {
    $boxx = 2*$opt_O;
    $boxy = 2*$opt_O;
    $boxz = 2*$opt_O;
    $outer = $opt_O;
  } else {
    die "Error: the value for '-O' ($opt_O) is not a valid number\n       Please choose a positive real # value\n";
  } 
} else {
   die "Error: the outer radius of the sphere '-O' must be set\n";
}
if (defined($opt_I)){
  $nothingSelected = 0;
  if ($opt_I =~ /^[0-9]/) {
    $inner = $opt_I;
  } else {
    die "Error: the value for '-I' ($opt_I) is not a valid number\n       Please choose a positive real # value\n";
  }
} else {
  $inner = 0;
}
 
if ($nothingSelected == 1) {
    die "(For help, use the \'-h\' option.)\n";
}
 
# open the file writer
open(OUTFILE, ">./$fileName") || die "Error: can't open file $fileName\n";
 
# check to set magic lattice numbers
if ($lattice == 0){
  $a = (4*18.01/(0.602*$density))**(1.0/3.0);
  $acut = $rcut * sqrt(2.0);
  if ($acut > $a) {
     $a = $acut;
     $newDensity = 4.0*18.01/(0.602*$a**3);
     print "using density of $newDensity to match cutoff value ($rcut)\n";
  }
} elsif ($lattice == 1){
  $a = (18.01/(0.602*$density))**(1.0/3.0);
  $acut = $rcut;
  if ($acut > $a) {
     $a = $acut;
     $newDensity = 18.01/(0.602*$a**3);
     print "using density of $newDensity to match cutoff value ($rcut)\n";
  }
}
$nxFloat = $boxx/$a;
$nx = int($nxFloat + $nxFloat/abs($nxFloat*2));
$nyFloat = $boxy/$a;
$ny = int($nyFloat + $nyFloat/abs($nyFloat*2));
$nzFloat = $boxz/$a;
$nz = int($nzFloat + $nzFloat/abs($nzFloat*2));
 
$anew = min($boxx/$nx, $boxy/$ny, $boxz/$nz);
 
if ($anew < $acut) {
 $anew = $acut;
}
 
$nxFloat = $boxx/$anew;
$nx = int($nxFloat + $nxFloat/abs($nxFloat*2));
$nyFloat = $boxy/$anew;
$ny = int($nyFloat + $nyFloat/abs($nyFloat*2));
$nzFloat = $boxz/$anew;
$nz = int($nzFloat + $nzFloat/abs($nzFloat*2));
 
if ($lattice == 0) {
  $nMol = 4 * $nx * $ny * $nz;
} else {
  $nMol = $nx * $ny * $nz;
}
 
$newDensity = $nMol * $densityConvert / ($boxx*$boxy*$boxz);
 
if (abs($newDensity-$density) > $tolerance) {
  print "Resetting density to $newDensity to make chosen sphere radius work out\n";
}
$cellLengthX = $boxx/$nx;
$cellLengthY = $boxy/$ny;
$cellLengthZ = $boxz/$nz;
 
$cell2X = $cellLengthX*0.5;
$cell2Y = $cellLengthY*0.5;
$cell2Z = $cellLengthZ*0.5;
 
$centerx = 0.5 * $boxx;
$centery = 0.5 * $boxy;
$centerz = 0.5 * $boxz;
 
if ($lattice == 0) {
# build the unit cell
# molecule 0
  $xref[0] = 0.0;
  $yref[0] = 0.0;
  $zref[0] = 0.0;
# molecule 1
  $xref[1] = 0.0;
  $yref[1] = $cell2Y;
  $zref[1] = $cell2Z;
# molecule 2
  $xref[2] = $cell2X;
  $yref[2] = $cell2Y;
  $zref[2] = 0.0;
# molecule 3
  $xref[3] = $cell2X;
  $yref[3] = 0.0;
  $zref[3] = $cell2Z;
# assemble the lattice
  $counter = 0;
  for ($z = 0; $z < $nz ; $z++) {
    for ($y = 0; $y < $ny; $y++) {
      for ($x = 0; $x < $nx; $x++) {
        for ($uc = 0; $uc < 4; $uc++) {   
          $xtest = $xref[$uc] + $cellLengthX*$x - $centerx;
          $ytest = $yref[$uc] + $cellLengthY*$y - $centery;
          $ztest = $zref[$uc] + $cellLengthZ*$z - $centerz;
          $rtest = sqrt($xtest*$xtest + $ytest*$ytest + $ztest*$ztest);
          if (($rtest > $inner) && ($rtest < $outer)) {
                  $xCorr[$counter] = $xref[$uc] + $cellLengthX*$x - $centerx;
                  $yCorr[$counter] = $yref[$uc] + $cellLengthY*$y - $centery;
                  $zCorr[$counter] = $zref[$uc] + $cellLengthZ*$z - $centerz;
                  $counter++;
          }
        }
      }
    }
  }
 
} elsif ($lattice == 1) {
  # build the unit cell
  # molecule 0
  $xref[0] = $cell2X;
  $yref[0] = $cell2Y;
  $zref[0] = $cell2Z;
#assemble the lattice
  $counter = 0;
  for ($z = 0; $z < $nz ; $z++) {
    for ($y = 0; $y < $ny; $y++) {
      for ($x = 0; $x < $nx; $x++) {
          $xtest = $xref[0] + $cellLengthX*$x - $centerx;
          $ytest = $yref[0] + $cellLengthY*$y - $centery;
          $ztest = $zref[0] + $cellLengthZ*$z - $centerz;
          $rtest = sqrt($xtest*$xtest + $ytest*$ytest + $ztest*$ztest);
          if (($rtest > $inner) && ($rtest < $outer)) {
                  $xCorr[$counter] = $xref[0] + $cellLengthX*$x - $centerx;
                  $yCorr[$counter] = $yref[0] + $cellLengthY*$y - $centery;
                  $zCorr[$counter] = $zref[0] + $cellLengthZ*$z - $centerz;
                  $counter++;
          }
      }
    }
  }
}
$nMol = $counter;
 
writeOutFile();
print "The water box \"$fileName\" was generated.\n";
 
if ($opt_m){
  printWaterMD();
  print "The file \"water.inc\" was generated for inclusion in \"$fileName\"\n";
}
 
 
 
# this marks the end of the main program, below is subroutines
 
sub acos {
  my ($rad) = @_;
  my $ret = atan2(sqrt(1 - $rad*$rad), $rad);
  return $ret;
}
 
sub writeOutFile {
  # write out the header
  print OUTFILE "<OpenMD version=1>\n";
  findCutoff();
  printMetaData();
  printFrameData();
  print OUTFILE "    <StuntDoubles>\n";
 
  # write out the coordinates
  for ($i = 0; $i < $nMol; $i++) {
 
    $q0 = 1.0;
    $q1 = 0.0;
    $q2 = 0.0;
    $q3 = 0.0;
 
    if ($doRandomize == 1){
      $cosTheta = 2.0*rand() - 1.0;
      $theta = acos($cosTheta);
      $phi = 2.0*3.14159265359*rand();
      $psi = 2.0*3.14159265359*rand();
 
      $q0 = cos(0.5*$theta)*cos(0.5*($phi + $psi));
      $q1 = sin(0.5*$theta)*cos(0.5*($phi - $psi));
      $q2 = sin(0.5*$theta)*sin(0.5*($phi - $psi));
      $q3 = cos(0.5*$theta)*sin(0.5*($phi + $psi));
    }
 
    print OUTFILE "$i\tpq\t$xCorr[$i] $yCorr[$i] $zCorr[$i] ";
    print OUTFILE "$q0 $q1 $q2 $q3\n";
  }
 
  print OUTFILE "    </StuntDoubles>\n  </Snapshot>\n</OpenMD>\n";
}
 
sub printMetaData {
  print OUTFILE "  <MetaData>\n";
 
# print the water model or includes
  if ($opt_m){
    print OUTFILE "#include \"water.inc\"";
  } else {
    printWaterModel();
  }
  printFakeWater() if $invalidWater == 1;
 
# now back to the metaData output
  print OUTFILE "\n\ncomponent{
  type = \"$waterName\";
  nMol = $nMol;
}
 
ensemble = \"LangevinHull\";
forceField = \"Water\";
electrostaticSummationMethod = \"shifted_force\";
electrostaticScreeningMethod = \"damped\";
cutoffRadius = $cutoff;
switchingRadius = $cutoff;
dampingAlpha = $alpha;
usePeriodicBoundaryConditions = \"false\";
 
targetTemp = 300;
targetPressure = 1.0;
viscosity =  0.00890;
 
tauThermostat = 1e3;
tauBarostat = 1e4;
 
dt = 2.0;
runTime = 1e3;
 
tempSet = \"true\";
thermalTime = 10;
sampleTime = 100;
statusTime = 2;
  </MetaData>\n";
}
 
sub findCutoff {
  if ($boxy < $boxx) {
    $bm = $boxy;
  } else {
    $bm = $boxx;
  }
  if ($boxz < $bm) {
    $bm = $boxz;
  }
  $boxLength2 = 0.5*$bm;
  if ($boxLength2 > $cutoff){
    # the default is good
  } else {
    $cutoff = int($boxLength2);
  }
}
 
sub printFrameData {
print OUTFILE
"  <Snapshot>
    <FrameData>
        Time: 0
        Hmat: {{ $boxx, 0, 0 }, { 0, $boxy, 0 }, { 0, 0, $boxz }}
    </FrameData>\n";
}
 
sub printWaterMD {
  open(WATERMD, ">./water.inc") || die "Error: can't open file water.inc\n";
  $waterFileHandle = 'WATERMD';
 
  print WATERMD "#ifndef _WATER_INC_\n#define _WATER_INC_\n";
  printCl();
  printNa();
  printSSD_E();
  printSSD_RF();
  printSSD();
  printSSDQ();
  printSSDQO();
  printSSD1();
  printTRED();
  printTIP3P();
  printTIP4P();
  printTIP4PIce();
  printTIP4PEw();
  printTIP4P2005();
  printTIP5P();
  printTIP5PE();
  printNE6();
  printSPCE();
  printSPC();
  printSPCHW();
  printDPD();
  printCG2();
  print WATERMD "\n\n#endif";
}
 
sub printCl {
  print $waterFileHandle "\n\nmolecule{
  name = \"Cl-\";
 
  atom[0]{
    type = \"Cl-\";
    position(0.0, 0.0, 0.0);
  }
}"
}
 
sub printNa {
  print $waterFileHandle "\n\nmolecule{
  name = \"Na+\";
 
  atom[0]{
    type = \"Na+\";
    position(0.0, 0.0, 0.0);
  }
}"
}
 
sub printSSD_E {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSD_E\";
 
  atom[0]{
    type = \"SSD_E\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printSSD_RF {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSD_RF\";
 
  atom[0]{
    type = \"SSD_RF\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printSSD {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSD\";
 
  atom[0]{
    type = \"SSD\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printSSDQ {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSDQ\";
 
  atom[0]{
    type = \"SSDQ\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printSSDQO {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSDQO\";
 
  atom[0]{
    type = \"SSDQO\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printSSD1 {
  print $waterFileHandle "\n\nmolecule{
  name = \"SSD1\";
 
  atom[0]{
    type = \"SSD1\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
}"
}
 
sub printTRED {
  print $waterFileHandle "\n\nmolecule{
  name = \"TRED\";
 
  atom[0]{
    type = \"TRED\";
    position( 0.0, 0.0, 0.0 );
    orientation( 0.0, 0.0, 0.0 );
  }
  atom[1]{
    type = \"EP_TRED\";
    position( 0.0, 0.0, 0.5 );
  }
 
  rigidBody[0]{
    members(0, 1);
  }
 
}"
}
 
sub printTIP3P {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP3P\";
 
  atom[0]{
    type = \"O_TIP3P\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP3P\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP3P\";
    position( 0.0, -0.75695, 0.52032 );
  }
 
  rigidBody[0]{
    members(0, 1, 2);
  }
 
}"
}
 
sub printTIP4P {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP4P\";
 
  atom[0]{
    type = \"O_TIP4P\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP4P\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP4P\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP4P\";
    position( 0.0, 0.0, 0.08444 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3);
  }
 
}"
}
 
sub printTIP4PIce {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP4P-Ice\";
 
  atom[0]{
    type = \"O_TIP4P-Ice\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP4P-Ice\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP4P-Ice\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP4P-Ice\";
    position( 0.0, 0.0, 0.09214 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3);
  }
 
}"
}
 
sub printTIP4PEw {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP4P-Ew\";
 
  atom[0]{
    type = \"O_TIP4P-Ew\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP4P-Ew\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP4P-Ew\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP4P-Ew\";
    position( 0.0, 0.0, 0.05944 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3);
  }
 
}"
}
 
sub printTIP4P2005 {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP4P-2005\";
 
  atom[0]{
    type = \"O_TIP4P-2005\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP4P-2005\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP4P-2005\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP4P-2005\";
    position( 0.0, 0.0, 0.08904 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3);
  }
 
}"
}
 
sub printTIP5P {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP5P\";
 
  atom[0]{
    type = \"O_TIP5P\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP5P\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP5P\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP5P\";
    position( 0.57154, 0.0, -0.46971 );
  }
  atom[4]{
    type = \"EP_TIP5P\";
    position( -0.57154, 0.0, -0.46971 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3, 4);
  }
 
}"
}
 
sub printTIP5PE {
  print $waterFileHandle "\n\nmolecule{
  name = \"TIP5P-E\";
 
  atom[0]{
    type = \"O_TIP5P-E\";
    position( 0.0, 0.0, -0.06556 );
  }
  atom[1]{
    type = \"H_TIP5P\";
    position( 0.0, 0.75695, 0.52032 );
  }
  atom[2]{
    type = \"H_TIP5P\";
    position( 0.0, -0.75695, 0.52032 );
  }
  atom[3]{
    type = \"EP_TIP5P\";
    position( 0.57154, 0.0, -0.46971 );
  }
  atom[4]{
    type = \"EP_TIP5P\";
    position( -0.57154, 0.0, -0.46971 );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3, 4);
  }
 
}"
}
 
sub printNE6 {
    print $waterFileHandle "\n\nmolecule{
  name = \"NE6\";
 
  atom[0]{
    type = \"O_NE6\";
    position( 0.0, 0.0, 0.0 );
  }
  atom[1]{
    type = \"H_NE6\";
    position( 0.0, 0.576029, 0.79283665 );
  }
  atom[2]{
    type = \"H_NE6\";
    position( 0.0, -0.576029, 0.79283665 );
  }
  atom[3]{
    type = \"EP_NE6\";
    position( 0.0, 0.23, 0.0 );
  }
  atom[4]{
    type = \"LP_NE6\";
    position( 0.732813007, -0.50364843, 0.0  );
  }
  atom[5]{
    type = \"LP_NE6\";
    position( -0.732813007, -0.50364843, 0.0  );
  }
 
  rigidBody[0]{
    members(0, 1, 2, 3, 4, 5);
  }
}"
}
 
sub printSPCE {
print $waterFileHandle "\n\nmolecule{
  name = \"SPCE\";
 
  atom[0]{
    type = \"O_SPCE\";
    position( 0.0, 0.0, -0.06461 );
  }
  atom[1]{
    type = \"H_SPCE\";
    position( 0.0, 0.81649, 0.51275 );
  }
  atom[2]{
    type = \"H_SPCE\";
    position( 0.0, -0.81649, 0.51275 );
  }
 
  rigidBody[0]{
    members(0, 1, 2);
  }
 
}"
}
 
sub printSPC {
print $waterFileHandle "\n\nmolecule{
  name = \"SPC\";
 
  atom[0]{
    type = \"O_SPC\";
    position( 0.0, 0.0, -0.06461 );
  }
  atom[1]{
    type = \"H_SPC\";
    position( 0.0, 0.81649, 0.51275 );
  }
  atom[2]{
    type = \"H_SPC\";
    position( 0.0, -0.81649, 0.51275 );
  }
 
  rigidBody[0]{
    members(0, 1, 2);
  }
 
}"
}
 
 
sub printSPCHW {
print $waterFileHandle "\n\nmolecule{
  name = \"SPC-HW\";
 
  atom[0]{
    type = \"O_SPC-HW\";
    position( 0.0, 0.0, -0.06461 );
  }
  atom[1]{
    type = \"D_SPC-HW\";
    position( 0.0, 0.81649, 0.51275 );
  }
  atom[2]{
    type = \"D_SPC-HW\";
    position( 0.0, -0.81649, 0.51275 );
  }
 
  rigidBody[0]{
    members(0, 1, 2);
  }
 
}"
}
 
sub printDPD {
  print $waterFileHandle "\n\nmolecule{
  name = \"DPD\";
 
  atom[0]{
    type = \"DPD\";
    position(0.0, 0.0, 0.0);
  }
}"
}
 
sub printCG2 {
  print $waterFileHandle "\n\nmolecule{
  name = \"CG2\";
 
  atom[0]{
    type = \"CG2\";
    position(0.0, 0.0, 0.0);
  }
}"
}
 
sub printFakeWater {
  print $waterFileHandle "\n\nmolecule{
  name = \"$waterName\";
 
  atom[0]{
    type = \"$waterName\";
    position(0.0, 0.0, 0.0);
  }
}"
}
 
 
sub validateWater {
  if    ($waterName eq 'Cl-')      { $waterCase = 0;    }
  elsif ($waterName eq 'Na+')      { $waterCase = 1;    }
  elsif ($waterName eq 'SSD_E')    { $waterCase = 2;    }
  elsif ($waterName eq 'SSD_RF')   { $waterCase = 3;    }
  elsif ($waterName eq 'SSD')      { $waterCase = 4;    }
  elsif ($waterName eq 'SSD1')     { $waterCase = 5;    }
  elsif ($waterName eq 'TIP3P')    { $waterCase = 6;    }
  elsif ($waterName eq 'TIP4P')    { $waterCase = 7;    }
  elsif ($waterName eq 'TIP4P-Ew') { $waterCase = 8;    }
  elsif ($waterName eq 'TIP5P')    { $waterCase = 9;    }
  elsif ($waterName eq 'TIP5P-E')  { $waterCase = 10;   }
  elsif ($waterName eq 'SPCE')     { $waterCase = 11;   }
  elsif ($waterName eq 'SPC')      { $waterCase = 12;   }
  elsif ($waterName eq 'DPD')      { $waterCase = 13;   }
  elsif ($waterName eq 'CG2')      { $waterCase = 14;   }
  elsif ($waterName eq 'SSDQ')     { $waterCase = 15;   }
  elsif ($waterName eq 'SSDQO')    { $waterCase = 16;   }
  elsif ($waterName eq 'TIP4P-Ice'){ $waterCase = 17;   }
  elsif ($waterName eq 'TIP4P-2005'){ $switchCase = 18; }
  elsif ($waterName eq 'SPC-HW')   { $waterCase == 19;  }
  elsif ($waterName eq 'NE6')      { $waterCase == 20;  }
  else                             { $invalidWater = 1; }
}
 
sub printWaterModel {
  if    ($waterCase == 0)  { printCl();      }
  elsif ($waterCase == 1)  { printNa();      }
  elsif ($waterCase == 2)  { printSSD_E();   }
  elsif ($waterCase == 3)  { printSSD_RF();  }
  elsif ($waterCase == 4)  { printSSD();     }
  elsif ($waterCase == 5)  { printSSD1();    }
  elsif ($waterCase == 6)  { printTIP3P();   }
  elsif ($waterCase == 7)  { printTIP4P();   }
  elsif ($waterCase == 8)  { printTIP4PEw(); }
  elsif ($waterCase == 9)  { printTIP5P();   }
  elsif ($waterCase == 10) { printTIP5PE();  }
  elsif ($waterCase == 11) { printSPCE();    }
  elsif ($waterCase == 12) { printSPC();     }
  elsif ($waterCase == 13) { printDPD();     }
  elsif ($waterCase == 14) { printCG2();     }
  elsif ($waterCase == 15) { printSSDQ();    }
  elsif ($waterCase == 16) { printSSDQO();   }
  elsif ($waterCase == 17) { printTIP4PIce();}
  elsif ($waterCase == 18) { printTIP4P2005();}
  elsif ($waterCase == 19) { printSPCHW();   }
  elsif ($waterCase == 20) { printNE6();     }
}