#!/bin/sh

# run from directory where this script is
cd `echo $0 | sed 's/\(.*\)\/.*/\1/'` # extract pathname
EXAMPLE_DIR=`pwd`

# check whether echo has the -e option
if test "`echo -e`" = "-e" ; then ECHO=echo ; else ECHO="echo -e" ; fi

$ECHO
$ECHO "$EXAMPLE_DIR : starting"
$ECHO
$ECHO "This example shows how to use pw.x to perform molecular dynamics for"
$ECHO "2- and 8-atom cells of Si starting with compressed bonds along (111)."

# set the needed environment variables
. ../../../environment_variables

# required executables and pseudopotentials
BIN_LIST="pw.x"
PSEUDO_LIST="Si.pz-vbc.UPF"

$ECHO
$ECHO "  executables directory: $BIN_DIR"
$ECHO "  pseudo directory:      $PSEUDO_DIR"
$ECHO "  temporary directory:   $TMP_DIR"
$ECHO "  checking that needed directories and files exist...\c"

# check for directories
for DIR in "$BIN_DIR" "$PSEUDO_DIR" ; do
    if test ! -d $DIR ; then
        $ECHO
        $ECHO "ERROR: $DIR not existent or not a directory"
        $ECHO "Aborting"
        exit 1
    fi
done
for DIR in "$TMP_DIR" "$EXAMPLE_DIR/results" ; do
    if test ! -d $DIR ; then
        mkdir $DIR
    fi
done
cd $EXAMPLE_DIR/results

# check for executables
for FILE in $BIN_LIST ; do
    if test ! -x $BIN_DIR/$FILE ; then
        $ECHO
        $ECHO "ERROR: $BIN_DIR/$FILE not existent or not executable"
        $ECHO "Aborting"
        exit 1
    fi
done

# check for pseudopotentials
for FILE in $PSEUDO_LIST ; do
    if test ! -r $PSEUDO_DIR/$FILE ; then
       $ECHO
       $ECHO "Downloading $FILE to $PSEUDO_DIR...\c"
            $WGET $PSEUDO_DIR/$FILE $NETWORK_PSEUDO/$FILE 2> /dev/null
    fi
    if test $? != 0; then
        $ECHO
        $ECHO "ERROR: $PSEUDO_DIR/$FILE not existent or not readable"
        $ECHO "Aborting"
        exit 1
    fi
done
$ECHO " done"

# how to run executables
PW_COMMAND="$PARA_PREFIX $BIN_DIR/pw.x $PARA_POSTFIX"
$ECHO
$ECHO "  running pw.x as: $PW_COMMAND"
$ECHO

# MD in a 2-atom cell
cat > si.md2.in << EOF
 &control
    calculation='md'
    restart_mode='from_scratch',
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/',
    dt=20,
    nstep=100,
    disk_io='high'
 /
 &system
    ibrav= 2, celldm(1)=10.18, nat=  2, ntyp= 1,
    ecutwfc = 8.0, nosym=.true.
 /
 &electrons
    conv_thr =  1.0d-8
    mixing_beta = 0.7
 /
 &ions
    pot_extrapolation='second-order'
    wfc_extrapolation='second-order'
 /
ATOMIC_SPECIES
 Si  28.086  Si.pz-vbc.UPF
ATOMIC_POSITIONS
 Si -0.123 -0.123 -0.123
 Si  0.123  0.123  0.123
K_POINTS {automatic}
 1 1 1 0 0 0
EOF
$ECHO "  running the MD calculation for Si in a 2 atom cell. G-point...\c"
$PW_COMMAND < si.md2.in > si.md2.out
check_failure $?
$ECHO " done"

awk '/Ekin/{ek=$3;et=$11; print it,time,ek,u,et}/Dynamics/{it=$5;time=$8}/^\!/{u=$5}' si.md2.out > MD2

# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/pwscf*
$ECHO " done"

# MD in a 8-atom cell
cat > si.md8.in << EOF
 &control
    calculation='md'
    restart_mode='from_scratch',
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/',
    dt=20,
    nstep=100,
    disk_io='high'
 /
 &system
    ibrav= 1, celldm(1)=10.18, nat=  8, ntyp= 1,
    ecutwfc = 8.0, nosym=.true.
 /
 &electrons
    conv_thr =  1.0d-8,
    mixing_beta = 0.7
 /
 &ions
    pot_extrapolation='second-order'
    wfc_extrapolation='second-order'
 /
ATOMIC_SPECIES
 Si  28.086  Si.pz-vbc.UPF
ATOMIC_POSITIONS
 Si -0.123 -0.123 -0.123
 Si  0.377  0.377 -0.123
 Si  0.377 -0.123  0.377
 Si -0.123  0.377  0.377
 Si  0.123  0.123  0.123
 Si  0.623  0.623  0.123
 Si  0.623  0.123  0.623
 Si  0.123  0.623  0.623
K_POINTS {automatic}
 1 1 1 0 0 0
EOF
$ECHO "  running the MD calculation for Si in a 8 atom cell. G-point...\c"
$PW_COMMAND < si.md8.in > si.md8.out
check_failure $?
$ECHO " done"

awk '/Ekin/{ek=$3;et=$11; print it,time,ek,u,et}/Dynamics/{it=$5;time=$8}/^\!/{u=$5}' si.md8.out > MD8

# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/pwscf*
$ECHO " done"

# MD in a 2-atom cell. Gamma+3X
cat > si.md2_G3X.in << EOF
 &control
    calculation='md'
    restart_mode='from_scratch',
    pseudo_dir = '$PSEUDO_DIR/',
    outdir='$TMP_DIR/',
    dt=20,
    nstep=100,
    disk_io='high'
  /
 &system
    ibrav= 2, celldm(1)=10.18, nat=  2, ntyp= 1,
    ecutwfc = 8.0, nosym=.true.
 /
 &electrons
    conv_thr =  1.0d-8,
    mixing_beta = 0.7
 /
 &ions
    pot_extrapolation='second-order'
    wfc_extrapolation='second-order'
 /
ATOMIC_SPECIES
 Si  28.086  Si.pz-vbc.UPF
ATOMIC_POSITIONS
 Si -0.123 -0.123 -0.123
 Si  0.123  0.123  0.123
K_POINTS
 4
 0.0 0.0 0.0 1.0
 1.0 0.0 0.0 1.0
 0.0 1.0 0.0 1.0
 0.0 0.0 1.0 1.0
EOF
$ECHO "  running the MD calculation for Si in a 2 atom cell. G3X-points...\c"
$PW_COMMAND < si.md2_G3X.in > si.md2_G3X.out
check_failure $?
$ECHO " done"

# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/pwscf*
$ECHO " done"

awk '/Ekin/{ek=$3;et=$11; print it,time,ek,u,et} \
     /Dynamics/{it=$5;time=$8}/^\!/{u=$5}' si.md2_G3X.out > MD2_G3X

$ECHO
$ECHO "$EXAMPLE_DIR: done"